Skip Navigation

Metra GMOS-01 Wiring Interface

Connect a new car stereo and retain OnStar®, factory door chimes, and audible safety warnings in select GM vehicles

141 Reviews | 7 questions - 11 answers

Find what fits your vehicle

Or choose one of your previously selected vehicles:

Can't find your exact vehicle?

Item #: 120GMOS01

In Stock

Add to Cart

Ask an expert

Our VA-based experts can help.

1.888.955.6000

ChatEmail

Add to Cart

$79.99

Overview

Our take on the Metra GMOS-01 Wiring Interface

Metra's GMOS-01 interface lets you replace the factory radio in select OnStar-equipped 2000-up GM vehicles using the existing wiring and connectors. Even if you don't subscribe to OnStar, you'll need this interface to connect an aftermarket stereo.

Metra's GMOS-01 interface lets you replace the factory radio in select OnStar-equipped 2000-up GM vehicles using the existing wiring and connectors. Even if you don't subscribe to OnStar, you'll need this interface to connect an aftermarket stereo.

Hook the GMOS-01 to your aftermarket radio, mount the module, and plug it into the existing factory plug. Get the great sound you want, and keep all important safety features intact. And you can adjust volume settings for OnStar as well as the safety chimes. Also, once you turn off the ignition in these GM vehicles, the radio continues to play until you open the door. This interface maintains that function with your new aftermarket radio.

This interface is compatible with select 2000-up GM vehicles. If you haven't done so already, please enter your vehicle information or call an Advisor at 1-888-955-6000 to find out if this item is compatible with your vehicle. Warranty: 1 year.

Note: The GMOS-01 will not work with factory-installed Bose car audio systems.

Note: Most vehicles will require additional installation parts — please identify your vehicle if you haven’t done so. You can also call an Advisor for more information.

works well, easy to install, had all connections necessary for rear view camera operation.

Brian, Littleton, CO

What's in the Box:

  • GMOS-01 Class II Data Bus interface
  • Wiring harness with 10-pin Molex on one end and bare wires on the other
  • Wiring Harness with 12-pin Molex on one end and 24-pin Molex and 12-pin Molex on the other (plus bare wires)
  • Installation instructions
Reviews

Metra GMOS-01 Wiring Interface Reviews

Average Customer Review:

141 Reviews

Install kit

Brian from Littleton, CO on 8/27/2016

2009 GMC Canyon
Crutchfield Customer Review (What's this?)

works well, easy to install, had all connections necessary for rear view camera operation.

Pros: I like that it ducks the front speakers for warning chimes.

Cons:

Clean and easy install, Retained all OEM functions

Curtis from Queen Creek, AZ on 7/19/2016

2012 GMC Canyon
Crutchfield Customer Review (What's this?)

Very clean and easy install, The size of the box made me a little nervous about it possibly rattling in my dash but its been installed for 3 years and not a sound!

Pros: Easy install

Cons: Maybe include some foam to wrap the unit to avoid rattles.

Needed accessory

Scott from Bethlehem, PA on 6/13/2016

2003 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

Has all the features to keep your vehicle in OEM operating condition.

Pros: Works great, all features retained as expected

Cons: Instructions are a little tough to follow. Plugs do not securely lock into module. Mine came apart twice during installation.

Gmos01 for 2012 canyon

Ger from Bound Brook NJ on 6/9/2016

2012 GMC Canyon
Crutchfield Customer Review (What's this?)

Works as described.

Pros: Works fine.

Cons: A little bulky but you will find space behind your radio for it.

Great Product, Confusing Installation

Michael from Fairfax, CA on 6/3/2016

2002 GMC Envoy
Crutchfield Customer Review (What's this?)

The device itself works perfectly to make the "retained accessory power", chimes (and probably OnStar as well, but OnStar is broken on my GMC so I can't test) work with an aftermarket head unit. Unfortunately, the included instructions and wiring diagrams leave much to be desired - they don't explain that the two red wires should go together. After a call to Crutchfield I was able to complete installation and now the Metra GMOS-01 works well, though it is a bit pricey for what it is.

Pros: Lets you keep retained accessory power, chimes, and onstar with an aftermarket head unit.

Cons: For the price, the instructions should be perfect!

Metra GMOS-01 Wiring interface

Alex from Great Bend, KS on 4/10/2016

2008 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

It's doing what it's supposed to do. No complaints. Wired up fairly easy.

Pros: Wired up with no problems.

Cons: None so far.

Perfect

Wayne from marshfield, WI on 3/20/2016

Came with new head unit and worked just as advertised

Pros:

Cons:

Instructions are outdated but works fine

Chase from Morehead, KY on 3/8/2016

2008 GMC Canyon
Crutchfield Customer Review (What's this?)

The instructions are very vague and do not explain why you have extra wires (or what to do with them). After some frustration I was still able to wire my head unit correctly. I tested that my door chimes and OnStar worked correctly and I was good to go. Mine had two red wires (the instructions on mentioned one). I was able to figure out that both red wires need connected to the single red wire on the head unit harness. Simple enough. The remaining harness was leftover for steering wheel controls (which I do not have). I simply shrink wrapped the ends and left it alone. Works as it should, but shouldn't have been so confusing to wire up. I assume a call to Crutchfield would have remedied the problem, but I don't believe it should have been so difficult.

Pros: Works perfectly

Cons: Poor and confusing directions

Good harness though the instructions need a bit of work.

pbo from san jose, CA on 2/14/2016

2008 GMC Canyon
Crutchfield Customer Review (What's this?)

The harness is good and allows you to install an aftermarket stereo keeping OnStar and the door dings. The problem is, the instructions tell you to "connect the red wire" when there are two. Talking to both Crutchfield and Metra I was told to connect both together. The Web is littered with people asking about this and various answers from connecting both to connecting one to power and one to another accessory. In my conversations with Metra, I suggested they fix the instructions. Also, the wires themselves have "dimmer" listed on the wire that while it does dim the radio actually connects to the vehicle's illumination (for when the dash lights come on). I was concerned about possibly connecting the wrong wire as some have suggested mixing these up can damage the stereo. I bit of clarification on both of these would be welcome.

Pros: Easy to connect and wire up. Allows for use of OnStar and keeps normal door/alert chimes.

Cons: Instructions could be a bit clearer. Once I knew what to do with the two red wires and had confirmation that "dimmer" should connect to the interior lights, installation was a snap.

Axxess GMOS-01 GM 2000-UP

Jason M. from Minnesota on 2/14/2016

2012 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

I ordered this to install my aftermarket head unit and Alpine Power Pack in my 2012 Chevy Colorado, and I gotta say it was nothing but a headache. It's not my first time installing stereos, as I have done dozens, but this one is probably the worst one I have done. I took to the internet for better directions and still had no luck, even with the provided paper directions in front of me. Needless to say I had our local pro installer check it out and he said this won't work for me, even though it was a deemed a fit from Crutchfield. Even after he did a temporary install the speakers cut out every time the stupid chime went off, and there is no R.A.P. so when you shut the vehicle off the stereo is instantly off, whereas my radio stayed on just fine and everything worked in my 2006 Colorado with a cheaper wiring harness. I am hoping I can return this and get a full refund for it because I would of never bought it if I had known the headache it would give me. Save your money on this one, talk to your local shops for the correct wiring harness, I ended up spending $99 on theirs and as for problems, not a 1!

Pros: Was cheaper than the $129.99 part.

Cons: Directions suck, install is a headache, say goodbye to your music when the annoying chimes kick in.

Crutchfield response on February 15, 2016 Whenever you encounter a problem with anything you purchase from Crutchfield, especially a situation like this, please contact our Tech Support team. Purchases from Crutchfield can be returned or exchanged within 60 days of the purchase.

Man that's a lot of wires

Joshua from Atlanta, GA on 2/3/2016

2003 Chevrolet Venture
Crutchfield Customer Review (What's this?)

Worked great, and i'm sure it would be even better with better instructions. My vehicle didn't have steering wheel controls, back up camera, Nav or anything else so it was slightly overwhelming. I only needed about 1/2 the wires supplied and it was kinda difficult to determine which was which. The instructions were clear but only had one wiring diagram. They really should have more than one for the installs that don't require every cable.

Pros: Worked great, I really like the adjustable sound level for the door chimes

Cons: Too many wires for a simple install and only one wiring diagram for all possible installs

Worked well, but those two red wires though

Ralph H. from wichita falls, TX on 1/25/2016

2005 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

You have a lot going on with this harness. And the instructions are decent with the exception of the instructions referencing a red wire to connect to the head unit red ignition wire. But there are two of those red wires. A bit of a head scratcher. Called Crutchfield Support on Sunday Afternoon and they quickly told me to use both red wires. That got me going again..

Pros: Unit worked as advertised. Crutchfield sent everything I need for this install. Tech Support available on Sunday when I had time to do the install is HUGE!!

Cons: Perhaps Crutchfield could send a supplement to the manufacturer's instructions to clear up the 2 red wire thing.

Metra GMOS-01 Wiring Interface

Anonymous from Tennessee on 12/20/2015

2006 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

Worked as advertised. Not to hard to wire up. I would rate the task as intermediate .

Pros: Merta website has good install document.

Cons: Slightly small gauge wires but ok for 22 watt radio. Kind of a one product fits several applications, On Star, Steering wheel control. Would not let this discourage me from purchase.

Perfect!!!!!

RMiller from Ohio on 12/12/2015

Crutchfield Customer Review (What's this?)

This wiring harness worked perfectly for 08 Hummer!!!!

Pros:

Cons:

Directions need to be more clear

LazyBoy Driver from Maryland on 11/30/2015

2009 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

I bought this for 2009 Chevy Colorado. To me, the directions need to be more clear. You might laugh but add pictures of what the 16 pin and 12 pin connections are. I'm not an electrician so when I read the directions.....I started scratching my head. I watched videos online to try and figure it out. Ended up figuring it out by counting the pins on the connector. I had to e-mail the manufacturer because on the 16 pin connector, it told me to connect the red wire....well there were 2. I had to verify I was to connect both of them. They did reply back rather quickly so their customer support is outstanding. Once I connected everything and installed the harness to my new Pioneer DVD player and rearview camera, it worked like a champ. Was able to view the rearview camera with connections made via this harness....didn't have to cut into or splice into other wiring harness. I was able to keep my OEM warning chimes (chimes that sound when you leave your lights on or leave your keys in the ignition). Once I got over my frustration of how to connect it, it was easy to connect and install. All the new equipment worked as advertised. I was very happy once I figured out what the directions were talking about. If it wasn't for the directions, I would have given it a 5 star rating.

Pros: Kept my OEM warning chimes and was able to connect my new DVD player and rearview camera without having to splice into other harness.

Cons: Directions are clear enough.

Essential piece of euipment

John from Alabama on 11/22/2015

2009 GMC Canyon
Crutchfield Customer Review (What's this?)

Installed with a new Sony Unit and was able to maintain all factory functionality such as On Star, door chimes, etc.

Pros: Once the wiring diagram was figured out, made installation extremely simple and straight forward, taking all of about thirty minutes.

Cons: Like many other reviews state, the instructions for the wiring diagram are atrocious. Confusing and worst of all, incomplete.

Worked perfectly for 2006 chevy uplander.

Mindmatrix from Arizona on 11/2/2015

2006 Chevrolet Uplander
Crutchfield Customer Review (What's this?)

Worked perfectly for my 2006 chevy uplander.Instructions where vary limited,but if you follow them exactly and don't need to know what all the extra wires are for thay are sufficient.

Pros: Let's you use a aftermarket stereo.

Cons: Does not give you details on the additional 12 pin connector or what it's for.Makes you wounder why it has so many unused wires and whether you should cap them off.

Easy install

Dave from Arizona on 10/4/2015

2006 Hummer H3
Crutchfield Customer Review (What's this?)

Made the the installation easy

Pros: Customer support helpful.

Cons: Instructions voukd have been a little clearer.

Works great

Chris from Tennessee on 9/24/2015

2004 GMC Envoy
Crutchfield Customer Review (What's this?)

Put this in an '04 GMC Envoy. Easy enough wiring guide. Google any questions you might have about the wiring because odds are someone else has already gone through it.

Pros:

Cons:

GMOS-01

GM77 from Missouri on 9/8/2015

Crutchfield Customer Review (What's this?)

Good product, poor directions!

Pros: Worked just like advertised

Cons: Directions from Metr/Axxess were incomplete

Metra GMOS-01 Wiring Interface

Anonymous from North Carolina on 7/4/2015

2009 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

Great product, wiring diagram was clearly explained & connectors fit perfectly

Pros:

Cons:

Works well

Jade from Brandon fl 33511 on 6/25/2015

2002 Chevrolet TrailBlazer EXT
Crutchfield Customer Review (What's this?)

Worked perfectly

Pros: Fast hook up easy to use

Cons: None

good quality

Ike from Philadelphia, New York on 6/1/2015

2005 Chevrolet Avalanche
Crutchfield Customer Review (What's this?)

works great, plug and play item unless your using a steering wheel adaptor also but still a must have for proper installment.

Pros: high quality easy to use.

Cons: none

GMOS-01

JimmyC from Arizona on 5/30/2015

2005 GMC Envoy
Crutchfield Customer Review (What's this?)

Worked exactly as described. I carefully put together the harness with the GMOS-01 and the radio harness, soldering and heat shrinking all connections. When I installed the radio and plugged it all in, everything worked perfectly. Did have to call technical support on a couple of questions, namely the existence of an extra red wire on one connector that wasn't mentioned in the instructions (regardless of what you see on the inter-web, you do not need to connect both of them together and then to the ignition power input to the head unit, just use one of them and tape off the other or use it for power for something else) and extra orange and orange-white wires on the other connector (they were taped off in my application). Works flawlessly. I get all my chimes through the front speakers, then it ramps the sound back in after the chimes. My rig has On-Star, but I don't use it so I have no comment on that.

Pros: Integrates the factory wiring harness and uses all factory connectors and wiring to the speakers. The only wiring I did in the truck was to the add-on powered sub. Otherwise, the complete harness was assembled at my dining room table and was plug-and-play in the dash; no in the dash connections were required. Wires are color coded to factory wiring, so between the instructions and matching wires, it was easy sailing.

Cons: Instructions were not crystal clear and did not mention some of the wires.

Metra GMOS-01

JH from Santa Claus, IN on 5/26/2015

2008 GMC Canyon
Crutchfield Customer Review (What's this?)

Product works great, all of my factory items still work as they originally did. The only complaint I had was I thought the instructions could have been slightly more detailed. No complaints now that it's installed.

Pros: Retains all factory chimes and functionality.

Cons: Instructions could have been a little more detailed.

like it

Kevin from delphos, ohio on 4/28/2015

2004 GMC Envoy
Crutchfield Customer Review (What's this?)

Plugs right into my 04 gmc envoy

Pros: Makes it easier to hook radio to my car

Cons: Wiring is a lil bit hard to hook up

Quality harness for 2008 Chevy Colorado

Steve-F from Tennessee on 4/22/2015

2008 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

It seems like a ton of wires to connect and figure out, but it's really not that bad once you get started. I took my time and soldered all my connections to the stereo harness so they are all solid connections. Used the heat shrink sheathing to cover the solder connections.

Pros: Works great, no problems at all.

Cons: Some wires were not needed for my vehicle and that made it a little confusing trying to figure out what was what.

Perfect

Willis from North Carolina on 4/22/2015

2008 GMC Canyon
Crutchfield Customer Review (What's this?)

Easy to wire up, keeps all your lovely chimes and such (if you want).

Pros: Easy Setup, Works Perfect

Cons: None

Worked really well

Brian WV from West Virginia on 3/29/2015

2006 Hummer H3
Crutchfield Customer Review (What's this?)

Works so well on my h3 its awesome to have the correct wiring the first time with security it will be correct with home installs the first timer can use this product with ease! kept my onstar and hands free calling also

Pros: great ,comes with option wiring for steering wheel controls ans onstar is retained!

Cons: non

Does not Work

George from SA, Texas on 3/27/2015

Trying a simple Kenwood double din install in a 2005 Tahoe. I found the wiring instructions for the GMOS unit very simple, matched up well with both aftermarket radio and factory plug. However after 2 weeks of calls and emails traded with Metra tech support the unit will still not initialize. No chimes, no 12V to radio, nothing.

Pros: Straight foreword install. Tech support is available and responsive

Cons: Doesn't work

Harness for Chevy Trailblazer

Jake from Arizona on 3/23/2015

2007 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

So far the product has worked really well. I bought this to install an aftermarket cd player/tuner in a Chevy Trailblazer. Most of the wiring was pretty strait forward. The wire colors matched up pretty well with the wires from the new unit, except there were 2 red wires. Instructions were vague on this installation, however after a little research online the 2 red wires were suppose to be connected to the red constant power wire for the unit. Other than that everything else was a breeze.

Pros: For the most part pretty strait forward with connecting wires by color.

Cons: Picture wiring diagrams would help.

Works Great

CME from Michigan on 3/5/2015

2007 Hummer H3
Crutchfield Customer Review (What's this?)

Works great. It's a little intimidating at first sight but follow the directions and go one wire at a time.

Pros: Works great

Cons: looks intimidating

Great

Devon from Anchorage, AK on 2/15/2015

2007 Hummer H3
Crutchfield Customer Review (What's this?)

Great product, quick and easy to install. Had it wired and ready to go within 10 minutes.

Pros: Quick, easy, all the wires are labelled.

Cons: None

Metra GMOS-01 Wiring Interface

Anonymous from west haven ct on 2/15/2015

2005 Saturn Relay
Crutchfield Customer Review (What's this?)

Bought this product for my 05 Saturn Relay with on star. Replace factory radio with an aftermarket radio. Hooked up all the necessary wires & plugged into original harness in car. No problems with it so far.

Pros:

Cons:

Great product

Mb from New York on 2/9/2015

Crutchfield Customer Review (What's this?)

I had this installed in my 2005 GMC Envoy and it was an easy install. All the wiring matched perfect so it took half the time it normally would. Great product

Pros: Easy to install.

Cons: None

Bad instructions

Michael from Boston on 1/7/2015

2008 Pontiac Grand Prix
Crutchfield Customer Review (What's this?)

If only the instructions gave a complete guide of how to complete, then the product would be good

Pros:

Cons:

Crutchfield response on January 12, 2015 We forwarded this review to our Technical Support team for follow-up. Lifetime tech support comes with every Crutchfield purchase.

What was this for?

mmaxon888 from Fort Calhoun, NE on 10/15/2014

2004 Chevrolet Silverado 1500
Crutchfield Customer Review (What's this?)

Not even sure what this adapter was supposed to do. I was under the impression I would retain my steering wheel controls, but that is not the case. Doesn't look like I needed this part at all.

Pros: Easy to attach. Had question during install, Crutchfield customer service answered phone right away and fixed my issue. Knew exactly what I needed to plug in even though I didn't know exactly what I was asking for!

Cons: Did not do what I thought it would. In fact, it doesn't look like I needed the adapter at all.

Crutchfield response on October 21, 2014 Our Tech Support team helped clarify why the customer needed the GMOS-01 and helped him get the other feature he wanted (to retain his steering wheel controls) by adding the ASWC-1 adapter. The customer reports that he is completely happy with his new gear and found our service to be very helpful.

Metra GMOS-01 Wiring Interface

DennisK from Mendon, MA on 10/12/2014

2012 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

Not for the faint of heart. I am an electronics technician and I needed to call Crutchfield for assistance. Instructions are not great. These are one size fits many and there is no guidance as to what to do with the extra wires. Don't hesitate to call for assistance.

Pros: It works.

Cons: Poor instructions.

Works as advertised

Tom N. from Dillsburg PA on 9/2/2014

2012 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

I'm not sure what everyone complained about in these product reviews. I thought the instructions were easy to understand and that the product works as advertised. I read the instructions 1-2 times and then hooked it up to my new stereo step by step. I'll admit that upon first glance wiring this to the stereo can be daunting, but hooking every wire step by step turned out to be very simple

Pros: Everything that this is supposed to do (Bluetooth, OnStar) works

Cons: None

wiring

jim from Portsmouth, Va on 8/28/2014

2005 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

very easy to install and a great time saver

Pros:

Cons: none

Metra GMOS-01 Wiring Interface

Anonymous from Bedford, OH on 8/19/2014

Crutchfield Customer Review (What's this?)

Does what it says keep all factor options

Pros:

Cons:

metra gmos 01 factory intigration adapter

cris f. from hamilton,oh on 6/23/2014

Tricky but read it carefully all detailed well.

Pros: If u know what u r doing it's easy as 123!

Cons: None

Metra GMOS-01 Factory Integration Adapter

Tim from Aurora, CO on 6/20/2014

2004 Pontiac Grand Prix
Crutchfield Customer Review (What's this?)

I soldered all the wires so the went well

Pros: For my application it worked great.

Cons: Some of the wires could be longer to make connections easier.

Metra GMOS-01 Factory Integration Adapter

MikeO from Denver, CO on 5/18/2014

2008 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

Having to buy this otherwise Crutchfield won't support your service was a bit of a drag. But, after installing this I'm glad I put it in to retain the original chimes and OnStar.

Pros: Keeps the door chimes and OnStar. Easy to install.

Cons: Necessary purchase if Crutchfield support is desired.

Metra GMOS-01 Wiring Interface

Anonymous from Cumming, GA on 4/30/2014

2005 Chevrolet Avalanche
Crutchfield Customer Review (What's this?)

Hookup was quite simple; however, I had to google to determine the exact location for some of the wires. The instructions could be a little more clear and could have mentioned that there are two red wires but only one is necessary. Crutchfield didn't recommend the Steering Wheel Remote module as a needed accessory. It is mentioned in the details of the unit but not when you select the headunit. Only this and the mounting adapter came up as a needed accessories.

Pros: Works perfectly.

Cons: Had to research for details on some of the instructions as not all wires are mentioned in the instructions.

OnStar interface

Tom J from Newington, CT on 4/6/2014

Crutchfield Customer Review (What's this?)

I still do not have an AM antenna working

Pros: Works for interface

Cons: Incomplete instructions, can't get AM radio antenna to work.

Good harness

Zeke from Sun Prairie, WI on 4/4/2014

2006 Pontiac Grand Prix
Crutchfield Customer Review (What's this?)

This was the same harness that I had bought before from a certain electronics store but was charged about double there and it was even an return but anyways the harness is good and works great one thing was that I had a lot of extra wires that we're not needed for my stereo

Pros:

Cons:

works great

Julzee from Pittsburgh PA on 3/31/2014

2008 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

I really like the lower volume of the door and seat belt chimes. I don't always wear my seat belt and the intermittent 'nagging' always got on my nerves but not any more...:)

Pros: nice soft chime vs original louder nagging

Cons: none

Great product

Anonymous from lagrange ky on 3/15/2014

2005 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

I had to buy thus adapter to install my Pioneer head unit because I have Onstar on my Chevy Trailblazer. Everything works great! Chimes even sound factory & not corney like some do! Once I got my old reciever out the adapter was very easy to install!

Pros: Factory sounding chimes Clear sound Easy install

Cons: A little more pricey than I wanted

Metra GMOS-01 Wiring Interface

2007trailblzr from Yadkinville, NC on 3/10/2014

2007 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

A must have when doing an install on a trailblazer it simplifies the process.

Pros: Makes the install almost seamless. Retains the onstar feature as well as the factory chimes.

Cons: No way to really control the volume of the chimes they are too loud.

Take your time and this will work.

RSS from Benton.Ar on 2/17/2014

2012 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

The product works well but the instruction manual isn't very clear. The manual doesn't give clear instructions on connecting the GMOS box , infact part of my manual was missing. With help from the Crutchfield tech (theses guys ROCK!) support I was able to complete the installation. Just be sure that all wires that are not used are taped up well and make contact with nothing or you will be replacing fuses. Found this out the hard way when some tape slipped off.

Pros: Works well and maintained all the safety features of my truck.

Cons: Instruction manual can get vague in some places. Pages were missing.

Does what it says

Chris M from Collegeville, PA on 2/6/2014

2006 Pontiac Grand Prix
Crutchfield Customer Review (What's this?)

Vehicle: 2006 Pontiac Grand Prix GT with factory radio (without Monsoon). Gear: Pioneer FH-X700bt, ASWC, GMOS-01 I will start by saying I have never installed a head unit before in my life. This was my first install. When you look at the GMOS-1, you might get intimidated by the mess of wires included with the Adapter. Don't be. As long as you are not color blind, installation is incredibly simple. The instructions are pretty easy to read too. I don't understand why people think they are confusing. I'll repeat, I have never installed a radio in my life. In fact this was the first time I have picked up a soldering iron. Trust me, if you have ANY cognitive skill at all, the directions are easy to follow. Functionality is dead on as described by the product. I LOVE that I can adjust the volume of the chime. Although I do hate the chime, I did not want to lose them. I am extremely happy that I can put the volume as low as I want. Integration with the ASWC interface is prety awesome. Again, those instructions are pretty simple to to follow as well. My steering wheel controls work flawlessly and I am very happy that I did not have to splice into the factory female harness. The GMOS-01 makes installing the ASWC even easier than it already is. Just get the dang GMOS and stop being cheap.

Pros: Chimes work (play through driver front speaker only) Adjustable chime volume RAP retained On Star retained ( I don't use it) ASWC integration NOTE: A lot of people are confused as to why there are two red (ignition) wires on the 16 pin harness of the GMOS-01. It is there in case you are using the ASWC. Connect one to your HU harness (doesn't matter which). Then connect the ASWC's harness red wire to other red wire in the 16 pin harness. Tape/cap it off if not using, duh.

Cons: Mess of wires, but common sense should tell you how to organize them for an easier install in the dash. Electrical tape or zip ties are your friends to group wires effeciently. Obviously, solder and heat shrink connections. Never seal an electrical connection with tape.

Metra GMOS-01 Wiring Interface

John O from Houston TX on 1/10/2014

Crutchfield Customer Review (What's this?)

I would like to start off by saying everything is setup and working great. Second, This harness is a universal setup for ALLLLot of vehicle models for alllll the different stereos so it scared me at first. I took the harness over to my uncles (ocd/electrical engineer). Yes he got it installed/wired/working. As everyone has stated the instructions borderline a writing nightmare. If you lay out the harnesses and get pigtail connectors on your stero harness you can easily get the harness hooked up fast. Yes there is about 9 wires I didnt use and to the OCD person it makes you double check everything. The system works great and retains all factory chimes and do-dads. 2006 base model envoy with pioneer deck.

Pros: It works

Cons: Have an extra 20 for the installer ready or buy them lunch

Metra GMOS-01 Wiring Interface

kyle from monroe Tennessee on 1/5/2014

Crutchfield Customer Review (What's this?)

Product was alittle intimidating at first due to the many wires. But with the help of directions included and the wires being color coordinated installation was easy.

Pros: Great directions and friendly customer service that was extremely helpful and knowledgeable

Cons: Two wires were not red like my factory car wiring harness but were pink instead. But they did have the correct writing on them which helped out.

Confusing, but works

BobF from New Orleans on 12/15/2013

Lots of extra wires, instructions not very detailed. After I hooked up the radio I had a problem with the sound, but after a couple of calls to tech. support everything is working fine. The reason I buy from Crutchfield is there customer service and tech support.

Pros:

Cons:

I've seen better

ZeeB from Manchester, NH on 12/12/2013

2006 GMC Canyon
Crutchfield Customer Review (What's this?)

The instructions are really quite thin, I had a bunch of extra wires left over at the end of putting this together. I ended up calling Crutchfield tech to sort things out.

Pros:

Cons:

Keeping the Chimes alive

Chris from Olathe, KS on 11/22/2013

2011 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

Very simple and straight forward to install. Wire diagrams and color coding made this a snap.

Pros: Keeps my factor chime intact.

Cons: Additional install.

Does the job!

DJ from Columbia, SC on 10/1/2013

2007 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

All the alarms and sounds were retained. That's what it is supposed to do.

Pros: Works well.

Cons: none

Great Product

DarrenG from Nebraska on 10/1/2013

Crutchfield Customer Review (What's this?)

Easy install, works as advertised.

Pros: Adjustable chime volume.

Cons: None

Works as promised.

Bob W from Shrewsbury, MA on 10/1/2013

2002 Pontiac Montana
Crutchfield Customer Review (What's this?)

Bought this to maintain my OnStar and factory chimes... Works perfect! Lots of wires including some extra that weren't needed for my install, but I figured it out by searching forums online.

Pros: Works well. Shuts off stereo for OnStar voice and turns it back on when OnStar is done.

Cons: OnStar voice only comes through front left speaker. Pricey (even with half off for buying a head unit at the same time) Wiring diagram could be more helpful.

Review for the Metra GMOS-01

Rich from Somers, NY on 9/24/2013

2005 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

Works as advertised. Haven't missed a beat with OnStar and door chimes. Wiring diagram was a little confusing, but Crutchfield tech support answered all of my questions.

Pros: No problems and works as advertised.

Cons: Wiring diagram

You get what you pay for

Josh from Michigan on 8/31/2013

Crutchfield Customer Review (What's this?)

I purchased this with a new pionner double din with the mixtrax,knowing little for what it was for.I've installed many decks and never had to use something like this.FIRST, theres alot of wires you wont use if you dont have a monsoon system or steering wheel controls.SECOND, theres two red power wires you have to twist together and connect to red power wire on deck,witch should have come pre-done or at least saying something about it the directions.THIRD,I dont like how chimes only come from drivers speaker,at first i thought i had it wired wrong but its normal i suppose.And the thing wont store my date and time on the dash anymore.Did Everything by the directions and even called Crutchfield for help,OVERALL this product works(sort of) but not in anyway near factory condition.Not happy with it.On a side note,Crutchfield's customer support is awesome,never been on hold more than 2 minutes and those guys really know what there doing. A+ to you guys in tech.As for you guys in the product buying department,you need to sit down with Metra and get these things fixed because even for the price,its not worth it.

Pros: dont really have one,just needed it

Cons: pain in the butt to install,low quality

Great for price.

Joeh24 from Dallas tx on 8/12/2013

2007 Hummer H3
Crutchfield Customer Review (What's this?)

For the price it's a great deal. 50% off with buying stereo.

Pros: Chimes volume adjustment,on star adjustment.

Cons: None

First one died secound one worked...

Dave C from Currituck, NC on 8/2/2013

2007 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

First time installer. I was a little confused with all the wires but I'm a technical person and had no problem figuring it out. The first unit work until I put everything back in and then the deck wouldn't come back on. It was just a Pioneer DEH-X5500HD, nothing special. So, I ran a double fuse wire to the deck and it worked. Then the battery started dieing so I asked around and no one could help. Then I called Crutchfield and they said it might be the brain. So, they sent me a new adapter and that one worked. I the problem is fixed and no more dead batteries. The only reason I gave this four stars and not five is because the first one died after I did all that work.

Pros: It's worked

Cons: First one worked then died

Worked for awhile

Tim from PortOrchard , WA on 7/24/2013

What they don't tell you; Chimes come from left front speaker only, low fuel chime is gone, and radio won't dim with lights on. Worked as I described, and learned to live with these faults. Now the deck goes into "protect" mode when I turn left randomly. Had the deck out numerous times and nothing is loose. popped the cover off the module, nothing appears loose. All connections are soldered and shrink wrapped. I have installed numerous decks over the years, so I am no new to this. I agree with the other review, wiring diagram is horrible. Not happy at all!

Pros: none

Cons: see review

Top Notch Product

Phil from Fresno, CA on 7/9/2013

2003 GMC Envoy
Crutchfield Customer Review (What's this?)

Adapter works very well with new receiver and factory equipment.

Pros: Good price, with receiver purchase.

Cons: None

GMOS-01

Jeff from Houston,TX on 7/8/2013

Crutchfield Customer Review (What's this?)

Installed in an 06 Suburban and hooked up to a JVC KD-A845BT alongside the Axxess ASWC-1. Everything works as advertised. I soldered and shrink wrapped all connections for a nice clean install. The completed harness was a mess with 2 interface boxes and multiple pig tails, but it all works.

Pros: Price, ease of install

Cons:

GMOS-01 Unreliable

kn from Atlantic. City on 7/7/2013

2008 Pontiac Grand Prix
Crutchfield Customer Review (What's this?)

Installed in my 2008 Grand Prix with a Kenwood navigation receiver, worked great for a few months. Then one night the receiver would not turn on. I removed the Kenwood and sent it for repair. Reinstalled the repaired Kenwood and it worked. This problem happened again in a few months, Kenwood was again repaired and reinstalled successfully. Next time this problem recurred, I unplugged everything then reinstalled: Kenwood worked without being repaired. Then it happened again. This time I simply unplugged the GMOS-01 connector then replugged it, and the Kenwood worked again! The problem was not the Kenwood receiver, but the intermittent faults in the GMOS-01.

Pros: Perform as described when it works

Cons: Unreliable. Keep shutting down the receiver randomly, requiring unplugging the GMOS.

GMOS-01 Factory Integration Adapter

JBroc from Philadelphia, PA on 6/12/2013

2007 Hummer H3
Crutchfield Customer Review (What's this?)

used in a 2007 Hummer H3, I had someone installed, but i called around for prices for this part. and Crutchfield beat it by $50.00! Just what I needed... and the price was GREAT!

Pros:

Cons:

easy

Anonymous from petersburg va on 6/11/2013

2006 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

I install my self is easy

Pros:

Cons:

GMOS-01 adapter cable

Tom from Albuquerque, NM on 5/9/2013

2005 Chevrolet Tahoe
Crutchfield Customer Review (What's this?)

Bought this to use with my new JVC KD-R740BT in my 2005 Chevy Tahoe. I am an electronic tech so all of the soldering of wires from the new deck cable to the adapter cable went well. Great instructions. Lots of extra bundles of cables to stuff back up into cavities.

Pros: All safety chimes work well. Crutchfield cuts price in half when you buy a deck from them at the same time. Nice deal but still darned expensive for an adapter cable with a small electronic interface box.

Cons: Not all connections were shown in drawing. Had some left over connectors but must not need them because everything is working fine. I would like to know what some of those extras are for. Cost is high.

Harness

Paul from Brandon, MS on 4/29/2013

2006 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

Worked as needed

Pros:

Cons:

GMOS-01 wiring harness

Clint from Santa Fe, NM on 4/27/2013

2003 Chevrolet TrailBlazer EXT
Crutchfield Customer Review (What's this?)

Fairly simple to install. One 45 second call to Crutchfield had all unused wires noted and the installation simplified.

Pros: Easy to install.

Cons: Instructions are almost perfect.

Does what it's suppose to

Lab4 from Wyoming on 4/18/2013

2005 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

Works like a charm for my '05 Colorado, but creates a mess of a wire harness when you get everything together. I am a bit OCD about trying to keep a clean look for all the wiring I do whether its car audio or home entertainment. it might all be hidden, but a clean install is easier to work on or add to. Even after I took some extra time trying to clean this thing up it still ends up looking like a knot of wire. I know that it is hidden, but it makes it hard to work on things under the dash. The instructions also do not cover the 3.5 male connector that is on one branch of this thing or the second lead on 16pin harness that goes with the new deck harness, but after a call to tech support with this question, which seemed to be a common one they get, I just taped the 3.5 branch outta the way and connected the extra lead together with the other 2.

Pros: Works easy install, as long as you follow the instructions.

Cons: it is a mess of wires

technology is a wonderful thing

Benjamin from Cleveland Ohio on 4/7/2013

2008 GMC Envoy
Crutchfield Customer Review (What's this?)

Using Crutchfield outfit my car app made finding the right part the first time so easy and hassle free. Once I received the part installing the part was not difficult at all. In fact the instruction sheet was barely read. Thanks Crutchfield.

Pros: Very very very easy to understand and install.

Cons: Taking it out of the package was a little rough. My blade wasn't sharp enough. Lol.

GMOS-01

Javier from Yuma, Az on 3/28/2013

Crutchfield Customer Review (What's this?)

Easy Instructions easy to use

Pros: Simple and easy love it

Cons:

Ok Stuff

BrianD from St. Clairsville, OH on 3/8/2013

2004 Pontiac Grand Prix
Crutchfield Customer Review (What's this?)

Not really sure about this one. The adapter is required for my car, 2004 Grand Prix, to still have door chimes.

Pros: Keeps my door chimes working. Assembled on workbench

Cons: Was not an easy install. Kind of confusing, but it is possible to figure out.

2011 Colorado crew can

Kory from Louisiana on 3/4/2013

2011 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

Works great. All factory safety alerts work and sound just like factory. Very easy to wire up.

Pros: You can do all wiring on work bench then plug in the pig tales to factory harness.

Cons:

GM Chimes Adaptor

Bill L from Texas on 2/26/2013

2006 GMC Envoy
Crutchfield Customer Review (What's this?)

This device works as advertised. Connections are a lot more difficult as compared to previous Crutchfield hook ups. I had to make 13 solder connections and blank off numerous wires. Thanks to Crutchfield's tech assistance it was manageable.

Pros: Works well Crutchfield tech support.

Cons: Lots of connections and little instructions.

Worked Perfectly!!

Al B. from Florence, SC on 2/23/2013

2003 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

This adapter was easy to install with perfect instructions for my vehicle and all factory chimes and OnStar worked flawlessly with my new Pioneer FXH-700BT stereo.

Pros: Ease of installation

Cons:

Works great!

Tibor from CA on 1/14/2013

2007 Pontiac Grand Prix
Crutchfield Customer Review (What's this?)

Works as it is supposed to.

Pros:

Cons:

Metra GMOS-01 installed in 2004 Envoy XUV

Stan from Atlanta, GA on 1/3/2013

2004 GMC Envoy XUV
Crutchfield Customer Review (What's this?)

Worked as designed. I selected this unit as I don't have steering wheel controls. Crutchfield adviser pointed me in the right direction to make the proper choice. I installed it in three steps. Matched wires to radio harness and twisted together. Soldered all wires and wrapped with electrical tape. Then neatened up the complete package with tie wraps. Installed in the Envoy with the Radio. Verified everything worked before putting dash and center console back together. One problem is that I should have adjusted the tone volume higher. I didn't take into account the higher radio volume once I started using it. I am an Electronics / computer geek, so I was able to read and understand the instructions / wiring diagram. Would be a little complicated for a person without some technical knowledge and should be left to a pro. The installation is only two weeks old.

Pros: Works as advertised. All functions work.

Cons: Comes with two red wires and had to call Crutchfield to get clarification. Turns out you can use either wire. This isn't in the manual / wiring diagram

Metra GMOS-01 Wiring Interface

Anonymous from joliet, IL on 1/2/2013

2005 GMC Canyon
Crutchfield Customer Review (What's this?)

works fine and has pretty good instructions for installation.

Pros:

Cons: for a first time car stereo installer, the instructions left too many things out. I ended up with multiple wires and plugs I wasn't sure what to do with that were left out of the instructions. All I had to do was tape them off and not use them but it still caused some confusion.

GMOS adapter

Allan from Florida on 12/26/2012

Crutchfield Customer Review (What's this?)

i rated this adapter so low because the NASA engineers wouldn't be able to decipher the wiring instructions.

Pros: it works

Cons: wiring instructions the worst i have ever seen

Does the job

Kevin F from Woburn, MA on 12/12/2012

Crutchfield Customer Review (What's this?)

The unit does what it is supposed to do. The door chimes, etc. all still work, as does the speaker. One small minus was that there were two different orange with white strip wires, I connected to the one described in the documentation, and the radio does not automatically dim at night. Don't know if would have worked with the other wire.

Pros: Keeps all of the integrated functions working.

Cons: Either the directions or my reading of them didn't work for dimming illumination.

Crutchfield response on December 18, 2012 We forwarded this review to our Technical Support team for follow-up. Lifetime tech support comes with every Crutchfield purchase.

Works like a charm

Neal S from Suffolk, VA on 8/18/2012

This thing works great. Installed in 03 Avalanche. Ill admit its overpriced and that the instructions are a bit lacking. It already has the wiring for steering wheel controls, all you need is the module, but you have to buy that package separately, or wait till the all-in-one set is in stock at Crutchfield, so you end up with an extra harness you dont use. I did use all the wires attaching to the head unit unlike other reviewers that didnt use them all. I was able to install it without any problems, or phone calls to tech support, and Im a long way from a pro stereo installer. Hopefully it will play well with the other kids, (in motion video bypass and wireless back-up camera when they show up in a few days) it is a lot to try to stuff back into the dash but eventually it fit. Thanks Crutchfield for the great customer service before the sale!

Pros: It works like it is supposed to!!

Cons: overpriced, although I got it for half price buying the Pioneer AVH 2400 BT

more than enough

David s from Elko, NV on 8/7/2012

2005 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

Product works as described, however. If you are not savvy at 12v electrical systems and this is your first stereo you will be lost. there are three parts of this harness, it is not plug and play, there is an optional harness that is not detachable so you have a dozen left over wires including a 12v hot wire that will be floating around under the dash sparking and shorting out all kinds of stuff if you do not secure it properly, not in the instructions, all in all it does what it is supposed to. amatures- get help!!!!

Pros: works as it is supposed to.

Cons: confusing, made for more options and non removable third part of not needed harness

Functions as Described

CC from North Carolina on 7/14/2012

2008 GMC Canyon
Crutchfield Customer Review (What's this?)

I wish I could have bypassed using this thing. I spent more time on figuring this out than I did the rest of my install. Instructions are somewhat vague. Took 3 calls to Crutchfield support to get things figured out but they were awesome and had the answers I needed right away. Each call only took about 5 minutes with no hold time. Props to the support team!!! Also, I did have to wire in a seperate speaker to hear my chimes. I simply used an old PC speaker I found laying around my workshop and it did the job. Unit has a very cheesy way of setting the Onstar volume control by actually shorting a wire to ground to get the setting you want.

Pros: Does what it's supposed to do.

Cons: Seems expensive even at half price. Instructions were vague.

GM Adaptor / OnStar

Mark from Birmingham, AL on 6/29/2012

Crutchfield Customer Review (What's this?)

Excellent piece of equipment. Very intimidating at first glance. Lot of wires, Lots of wires. Tech department offered some very patient and timely advice. Works perfectly but for a small glitch with the Onstar system. The reciever should mute when Onstar comes on. It does not. I must turn the reciever sound down to hear and talk with Onstar. Could be the install but the wires were specifically labled. No big deal.

Pros:

Cons:

GM Factory Integration Adapter

Mark G from NY on 6/17/2012

2005 Pontiac Grand Prix
Crutchfield Customer Review (What's this?)

I did not like this product. I could not figure out how to install it and did not use it.

Pros:

Cons:

Overpriced Installation Accessory

ElvinK from East Bank,WV on 6/3/2012

2008 Pontiac Grand Prix
Crutchfield Customer Review (What's this?)

Car manufacturs have ripped us off on the requirements to replace a factory radio. Plus the aftermarket manufactures have come in like vultures to price gouge. There is absolutely no reason why it should cost this much for this adapter (even at half price it is a little steep for no more than what it is). Plus it is not very reliable. For some reason, I have to unplug my connectors at the box and reconnect them to get it to work again. Does this randomly and cant figure it out.

Pros: Connects to factory wiring. Eases radio install.

Cons: Expensive. Unreliable.

Crutchfield response on June 6, 2012 We forwarded this review to our Technical Support team for follow-up. Lifetime tech support comes with every Crutchfield purchase.

2002 Trailblazer

Dennis from New Jersey on 5/27/2012

Crutchfield Customer Review (What's this?)

Great product, looks more complicated then it is. Installed in my 2002 Trailblazer and it did exactly what it was suppose to do.

Pros:

Cons:

Poor instructions but great service!

Ben from Raleigh, NC on 5/5/2012

Crutchfield Customer Review (What's this?)

Product works great. Instructions were pretty bad, and I had to call customer service twice to find out what to do with wires that were not addressed by the instructions. Customer Service was terrific and walked me through the wiring. Worked perfectly when I plugged it into the stereo.

Pros: Works Great. Great customer Service

Cons: Bad instructions

Works well in my Colorado

Bill from Jamestown, NY on 4/2/2012

2008 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

This should be free with the GM installation kit. The instructions were too technical, I ended up matching the colors of my GM harness and stereo then looking to see what was left. If you don't read the instructions, you could end up leaving a couple wires intact that you need to cut. At the end of the day - it worked, but its nothing to get excited about and is too expensive for what it is.

Pros: Keep your chimes and On Star

Cons: Expensive Poor instructions Extra wires left over that you don't use - the instructions don't tell you what they are for and that they may not be used Requires you to have a little more than common sense to hook up

A must have for applicable vehicles

defkon77 from norton, ohio on 4/2/2012

2009 GMC Canyon
Crutchfield Customer Review (What's this?)

I work on GM cars and understand how important this item is for A/M head units.....this installed easy,kept my vehicle like factory(retains RAP,uses door speaker chime, kept OnStar working like factory)....just before i bought this item I bought one from another retailer for twice the price( uses its on speaker and did not keep OnStar)....it was $90!!!...I returned it and bought this item instead

Pros: retains factory functions.....this imporant for safety and for any installer that cares about not being a "hack" when installing radios.

Cons: NONE!!!!

Fine

AznHammer from Winston Salem NC on 3/3/2012

2006 Hummer H3
Crutchfield Customer Review (What's this?)

Work great, and good price with for the on-star integration. It sucks that GM requires it, but the product works fine. As far as actual issues below talking about pops/chimes not working correctly, I wonder how much of that is an install problem. All my chimes are working as expected.

Pros: Cheapest one I've seen with on-star

Cons: I don't care of the new door chime sound.

Metra GMOS-01 Wiring Interface

capnrobi from Tampa FL on 2/12/2012

2008 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

I wonder if it was really necessary. My truck never had OnStar

Pros:

Cons:

Mostly works

AB from Rocky Mount, NC on 2/4/2012

2008 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

Installed in a 2008 Colorado and although most chimes work the way they used to, not all work.

Pros: Easy to install.

Cons: Not all chimes work correctly.

A necessary evil

Anonymous from Greenville SC on 1/31/2012

2007 Hummer H3
Crutchfield Customer Review (What's this?)

I hated the thought of spending the extra hundred bucks for this product, but the 50% off with head unit purchase made it palatable. Product works as described when installed properly. Do the splicing work on the bench, rather than in-car. Then, it's just plug-n-play when you go to mount it in the vehicle. The instruction set is minimal but it has all the necessary information.

Pros: Works as described.

Cons: Expensive but necessary.

adapter

j g from ft riley ks on 1/24/2012

2005 Chevrolet TrailBlazer EXT
Crutchfield Customer Review (What's this?)

great price, need to have product

Pros:

Cons:

Metra GMOS-01 Wiring Interface

ToddG from Potterville, MI on 1/19/2012

Crutchfield Customer Review (What's this?)

This item had one glaring problem when used with a 2008 Pontiac Grand Prix: The GMOS-1 would cause the driver's door speaker to make a loud, electrical 'pop' sound everytime you inserted the key into the ignition... or, if the key was in the ignition and you opened the door. It had to do with the GMOS-1 "Chime" function. I switched to the GM VT_GMRC-O1 instead, which has it's own built in 'factory style' chime speaker and then it worked flawlessly. I recommend using the GMRC-01 for this year/make of car. I did not have the Monsoon factory radio setup.... just the standard, run of the mill factory radio which I replaced with a JVC KWHDR720.

Pros: Everything worked great.... EXCEPT.... THE CHIME FUNCTION CREATED A STATIC/POP sound when key was inserted into ignition.

Cons:

Major Headache

Anonymous from Oklahoma City, OK on 12/17/2011

2007 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

1. Comes prewired with an additional connector and 3.5mm plug that the directions/pictures don't even address. 2. Lots of wires (not a big deal), throw in less than stellar directions, and you're left wondering. 3. Installation was pretty straight forward, thought I was good to go, worked perfect, until I came out to a dead battery the next day. Traced the problem to this unit feeding constant 12V power to the ACC wire. So the radio was always on. Yes, I double checked my wiring and everything was done according to the directions. The radio receives constant 12V direct from factor harness, but relies on the GMOS01 for the ACC 12V, so the problems was defiantly the unit.

Pros:

Cons:

Don't Over Think It

ag from Charleston, SC on 11/27/2011

2003 GMC Envoy
Crutchfield Customer Review (What's this?)

If a colorblind 22 year old can figure it out working out of the back of his SUV, at night, under a street light, anyone can. Yeah, it's a lot of wires and different colors, but if you match up exactly as the directions say and ignore the wires you don't use, you should be fine.

Pros: works well

Cons: a little confusing

Metra GMOS-01 Wiring Interface

chasjake from Cortland, Ohio on 10/6/2011

2011 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

Used this on a new stereo install in a 2011 Colorado. It works well. The wiring directions / diagram are a little tough to follow but I made it through. The chime is a little more sterile sounding that the factory chimes but who really cares.

Pros:

Cons:

Unorganized and Bulky!

JasonK from Kankakee, IL on 10/6/2011

2011 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

This thing is the most unorganized wiring harness I've ever seen! I took it out of the box and read the instructions for about 45 minutes trying to figure out where the extra black 12pin connector plugged into and the 3.5mm Male. Finally had to call Crutchfield and apparently its for a steering wheel control that's NOT EVEN MENTIONED ONCE in the instructions! Not to mention this thing is HUGE and I have a mid-size truck. Try fitting that in the dash!

Pros:

Cons:

Just as advertised

Johnson from Charleston,. SC on 8/30/2011

Crutchfield Customer Review (What's this?)

Pay attention to the directions and you'll be fine. Lots of wires, but easy to bundle together once all are connected. Made all the connections at the dining room table prior to installation and everything worked as described. Made the after market radio a seamless transition. Didn't need the On Star or amplifier options, so can't comment on them.

Pros:

Cons:

Directions are Confusing

JackR from Pittsburgh, PA on 8/6/2011

2006 Pontiac Grand Prix
Crutchfield Customer Review (What's this?)

READ INSTRUCTIONS CAREFULLY!!! They are very confusing, color codes on wiring are duplicated, and some additional explanation would have been helpful. Had to call Crutchfield twice to get it all figured out. Also the unit is quite big and you will need to find a location to put the box so it does not interfer with the radio and wiring. There has to be a simpler way to retain the factory chimes, but after all that, it does work well.

Pros:

Cons:

works

Cory from Eugene, OR on 7/18/2011

2007 Pontiac Grand Prix
Crutchfield Customer Review (What's this?)

works as advertised, maintains all factory features in my 2007 Grand Prix

Pros:

Cons:

ok but not great.

ivanE from Grand Rapids, MI on 7/2/2011

my stereo stays on untill i open the door, the chime work but you must have the aftermarket unit on if you remove the stereos faceplate it will no longer work. when hitting the onstar button the music won't go mute, thats something the factory unit used to do. I have installed a scosche one in a monte carlo 2001 and the chime works even if you remove the stereos face plate.

Pros:

Cons:

Metra GMOS-01 Wiring Interface

Anonymous from TAMPA FL. on 6/9/2011

Crutchfield Customer Review (What's this?)

WORKS AS ADVERTISED

Pros:

Cons:

2007 TrailBlazer w/o OnStar

stress from Pittsburgh, PA on 6/6/2011

2007 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

The device does exactly what it was designed to do. The installation was easy, even for someone who never messes with vehicle electronics. Don't forget that you'll need to buy some wire connectors and electrical tape! As for the tone, it honestly sounds just like the GM tone from the 80's. It's truly nothing bad -- and very easy to get used to.

Pros:

Cons:

OnStar adapter

Donnie from Vineland, NJ on 4/19/2011

Crutchfield Customer Review (What's this?)

Dont let all the wires scare you. It is & was a very easy install. At least on my Envoy it was. Tone takes a little getting used to, but not anoying

Pros:

Cons:

Overpriced But Works Flawless

Sundown from Upstate, NY on 3/28/2011

2008 Hummer H3
Crutchfield Customer Review (What's this?)

Wiring was extremely simple and took little to no time other then soldering. Once wired up, just plug it into the radio and factory harness and you are good to go. Still have OnStar, door chimes, and seatbelt chimes. Back up, park/parking brake and vehicle speed sensor are a big plus for installing a DVD, navigation or backup camera. I will say this item is EXTREMELY overpriced (half this price would be much more reasonable but thats what Crutchfield charges with a receiver purchase anways) and the quality is just good not great but it serves its purpose and works flawless. Review is based on a 2008 Hummer H3.

Pros:

Cons:

Like a SNAP!

Brian from Virginia on 3/27/2011

2008 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

Been some years since I changed an aftermarket stereo. I was going to pay and have it done for me, but a co-worker suggested Crutchfield. Not only did they walk me through what I needed, but the installation of this item was easier than you could imagine. Nowadays with electronics and the conglomeration of wires - IT CAN GET DISCOURAGING. It came with detailed instructions with the product and from Crutchfield - It was a piece of cake!

Pros:

Cons:

Better than the old ones

txplshrk from Corpus Christi TX on 3/14/2011

2008 Chevrolet Uplander
Crutchfield Customer Review (What's this?)

This one works a lot better than the old adapters. I had one just like this that sounded horrible, ever since they changed the design on this it seems to work better. Wiring connections are spot on and easy to follow. Be careful on how high you turn up the volume knob on this thing! Man it gets really loud.

Pros:

Cons:

work well

hope from chicago on 2/24/2011

Crutchfield Customer Review (What's this?)

this unit work well. was very easy to install and i have no problem with it

Pros:

Cons:

It's like I never switched out my old OEM stereo

EvansB from Arizona on 2/24/2011

2005 GMC Envoy
Crutchfield Customer Review (What's this?)

Bought this bad boy and was able to still hear my On Star and my Seat Beat/Door Open chimes. All I had to do was follow the instructions to turn up the volume on the OnStar audio.

Pros:

Cons:

Metra GMOS-01 Wiring Interface

Robert P from Phoenix, AZ on 2/6/2011

Crutchfield Customer Review (What's this?)

I used this kit to install a Clarion CD Receiver that I removed from another car. I am glad I saved the original wiring instructions from Crutchfield from the first installation. Soldering together all the wires was very time consuming but the wiring diagrams were easy to follow. I was amazed that red wire connected to red and blue to blue.....All the wire colors from the old Clarion matched this new kit. After installation, all chimes and warnings work just fine. I usually don't have this much luck on the first try.

Pros:

Cons:

Super Easy Install and Great Instructions

Deb from Hillsborough, NC on 1/31/2011

2008 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

The kit made the install really easy with detailed instructions. My dad is an electrician and watched me install. The instructions even addressed the function of the wires that are not used so when he asked me why I didn't use them I could point out they were for the back speakers we didn't have or if the radio had nav built in.

Pros:

Cons:

What a piece of junk!

Dirk C from Ellendale, ND on 10/9/2010

2002 Chevrolet Impala
Crutchfield Customer Review (What's this?)

Some of the wires had to be added on to, some of the wires were mismarked on the wires compared to what the documentation said. The documentation was contradictory. And worst of all, it just doesn't work. It doesn't chime, it cuts out the left speakers when error messages flash across the dashboard. The speed sensitive volume control doesn't work as advertised.

Pros:

Cons:

Metra GMOS-01 Wiring Interface

Derrick T from Fairview Heights, Il on 9/30/2010

Crutchfield Customer Review (What's this?)

I believe this module is really over priced and the instructions could be more detailed, but if you take your time, the average person can hook this module up. The main reason I purchased this module was to keep the warning chimes. Prior to installation in the dash, I turned the volume screw clockwise and counter clockwise and I still have not heard a chime yet. Other than that I guess it does what it suppose to do. After soldering all of those connections, I refuse to cut the wires and return it because of the warning chimes and waiting a week to 10 days for a replacement. Since I only paid half price and I was told this was not an optional part I guess I would recommend this to a friend but I would check it out complete before making all the final connections

Pros:

Cons:

Great product

Bob B from Seaford VA on 8/22/2010

2010 GMC Canyon
Crutchfield Customer Review (What's this?)

Outstanding product. Somewhat complicated to install but that's due to GMs complicated system, not the adapter. If you read the instructions carefully and apply some common sense it drops right in. Put this into a 2010 canyon WT worked 1st try. On-star didn't detect a thing - thinks the factory radio is still in it and all the On-star functions work perfectly.

Pros:

Cons:

Metra GMOS-01 Wiring Interface

Anonymous from Delaware on 8/18/2010

Crutchfield Customer Review (What's this?)

Worked great! Strait forward... Everything functions as it should, and the door chime is now a different tone, less annoying than the stock!

Pros:

Cons:

as advertised

Benny from Kansas City, MO on 6/15/2010

2008 Pontiac Grand Prix
Crutchfield Customer Review (What's this?)

This product works as advertised. The chimes were a little different than I was used to, but after a few weeks I don't think they are worse than the stock. Do test the chime loudness and adjust before putting the dash back together! The install was tedious due to the number of connections required (between 15-20 or so). Also, the instructions weren't exactly 100% clear at times, but I was able to figure it out once I started and got oriented with their wording. Once installed per the directions, it was simple to plug in and everything worked. It did take some creative positioning of all of the wires and the GMOS to get everything to fit, but it wasn't too difficult. All in all, this product really made installing an aftermarket head unit (CD Player) easy and trouble free. My antenna wasn't working quite right but Crutchfield's tech support was able to diagnose the problem, which was to connect all of the remote wires as directed by the instructions. Once that was performed, my radio reception was restored.

Pros:

Cons:

Skeptical

Angel from Chesapeake, VA on 5/3/2010

2003 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

When I first took this out of the box I was overwhelmed. So many wires and instructions. But it honestly wasn't that bad. Through the entire thing I only misconnected one wire (mute), and once I cut the wire the unit worked fine. It's been installed for two weeks, and it seems to be doing fine. My door chimes still don't work like they used to, but they do work. Just wish it wasn't necessary, that's a good chunk of change to lay on it.

Pros:

Cons:

Wroks well, questionable quality

Anonymous from Rochester, NY on 4/11/2010

2006 Pontiac Grand Prix
Crutchfield Customer Review (What's this?)

Once I got a unit that actually functioned, I found that it worked fine and supported all of the GM options that my car (2006 Grand Prix) had installed. The first unit shipped to me just did not work. Crutchfields's excellent phone support guys helped me determine this and they sent a new new one right away. This unit also had wires falling out of the connector - subpar build quality. The instructions are also fairly confusing although usable. I image that a novice would have a hard time with this. Crutchfield might save some support costs if they provided improved instructions for wiring up this unit.

Pros:

Cons:

Works Nicely

twenty4pack from Niceville, Florida on 9/20/2009

2003 Chevrolet Silverado 1500
Crutchfield Customer Review (What's this?)

The device works well, but the instructions were a bit confusing even though the wires were individually labeled. I bought it to work with a JVC KDA605 and my 2003 Silverado, and it does that almost perfectly. Single stepping through the instructions, I finally had everything soldered and insulated with heat shrink tubing. Surprised me the installation worked first time, and it's nice to have a door chime that's subdued. Only thing that bothers me is the instructions specified that the dimmer circuit would not work with my truck, even though the wires were available both coming from the OEM harness, the radio, and this adapter. I have not investigated further, having the display dim with the dash lights would be nice, but not worth the chance of destroying something.

Pros:

Cons:

IT WORKS!!!

Lee from Wichita, KS on 9/3/2009

2006 Pontiac Grand Prix
Crutchfield Customer Review (What's this?)

the instructions only include a wiring diagram for the amp and head unit installation. there is no diagram for the head unit only. i called cruthfield tech advisor 3 times for help and they had all the right answers. crutchfield tech support is the best. some of the wires are labeled the same, but serve different functions, which is where i got confused. cruthfield's tech advisors had me hook up the the amp wires even though i don't have an amp, because i have an amplified antenna in my son's 2006 pontiac grand prix. the instructions that come with the unit don't mention this, but crutchfield's tech guys were right. most everything works like a charm, except for the steering wheel controls no longer working. probably because my head unit doesn't support this feature, i guess. i wasn't sure i was going to have room for the GMOS behind the dash, but i had plenty. be sure to adjust your chime and onstar volumes before you put the dash back together, because they are on the GMOS unit. i had to cap off a few unused wires and the the harness connections fit perfectly. works great and my son loves his new stereo. kudos to crutchfield and there top of the line tech support.

Pros:

Cons:

"Retains On Star" not accurate

Anonymous from Xenia, OH on 8/29/2009

2008 Hummer H3
Crutchfield Customer Review (What's this?)

All works great, EXCEPT On Star part. After wiring, I could not make a call by hitting phone button on mirror. To me this is part of ON Star, but according to Metra, not really. They say I should be able to talk to ON Star advisor, but not make a phone call?!?!? The car is not home now, so cannot test veracity of reps' information. Had I known this to be the case, I would not have bought after market head unit. Now stuck.

Pros:

Cons:

Low quality

Douglas from Seattle, WA on 6/29/2009

2008 Pontiac Grand Prix
Crutchfield Customer Review (What's this?)

When I first opened the package, two wires fell out of the 14-pin harness. Not all of the wires from the factory plug run through the box, you will need to make connections from the radio harness straight to the factory harness. Pretty cheap design IMHO. I also had no luck with the mute wire(constantly muted when connected) and the dimmer wire doesn't work either, at least for my car(08 grand prix). The unit does retain the chimes(they are actually new chimes built into the GM0S-1) and the RAP feature.

Pros:

Cons:

works good- a lot of wires though

jasonv from phoenix, az on 4/23/2009

Crutchfield Customer Review (What's this?)

i made the mistake of hooking up all the brown 'mute' wires together and the 'att' (attention- its not the mute mode but it lowers the volumne way down) mode would keep coming on automatically. i am pretty good with wiring stuff and the directions are goofy so it took me awhile to figure it out. not sure why i wired them all together but just thought i'd throw that out there in case someone hooked up the wrong mute wire and can't get theirs to work right. it works for 2 different plugs so there are a lot of extra wires that weren't need for my '04 gmc canyon with no cd changer but with onstar.

Pros:

Cons:

product quality

Bryan from Jacksonville FL on 3/9/2009

2009 Chevrolet Colorado
Crutchfield Customer Review (What's this?)

the product quality over all is all right, the wiring schematic for an aftermarket stereo is strange i even called customer support and they did not have a schematic in there data base. All was eventually figured out with some confusion. the mute wire i had to cut b/c the gmos would not turn it off, now when onstar kicks on it shuts the radio off. the harness doesn't have pig tales for the rear speakers so you have to by pass the box to go straight to the factory adapter plug. with every thing finally wired up i plugged it in to the factory harness and the ground pin came out of the plug, thankfully i was able to lock the pin back in place. i guess it would be nice to have a harness i didn't have to bypass, or have it fall apart as i plug it in.

Pros:

Cons:

Metra GMOS-01 Wiring Interface

Ian from Lake Charles, Louisiana on 2/15/2009

2006 GMC Yukon XL
Crutchfield Customer Review (What's this?)

Did exactly what I wanted it to do. It was easy to install, but I wish it would automatically dim the screen when the lights are turned on.

Pros:

Cons:

not everything i expected...

kamaha`o from Maui, HI on 2/10/2009

Crutchfield Customer Review (What's this?)

This product does not operate exactly the way I imagined it would. I rate it a two because I like that the radio remains on in my car until I open the door, and the onstar works, but the chime is not the same and the dim feature does not work at night. I need to manually adjust my screen. The biggest problem I have with this unit is the chime because it stops sound from the radio coming out of the front left speaker to do the chime. Before, the radio would continue playing music and the chime would be audible at the same time. They said this was a very important part, which I agree it is, but I hope they can improve it in the future to work seamlessly. Installation guide was clear and although the many wires seemed intimidating at first, it was a breeze to get the job done.

Pros:

Cons:

For the novice installer

Granzow from Fort Wayne, IN on 2/8/2009

2004 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

I installed this on a 2004 Chevy Trailblazer with OnStar without Bose system. It's truly a plug-in and play device. The color-coded wires matched perfectly with my Kenwood DNX5120 Navigation radio. The DVD player works just fine. If you are thinking of installing yourself, don't be afraid because it is much easier than it looks.

Pros:

Cons:

Nice little box

O.V from Colorado on 1/29/2009

2007 GMC Envoy
Crutchfield Customer Review (What's this?)

Easy to hook up but will add a lot of wires so be sure you have the room. I upgraded the factory radio in my 2007 Envoy with a Kenwood KVT-512 head unit. I installed the GMOS-01 to keep the factory chimes. The only problem I have is it wont automaticly dim the screen when the headlights are turned on but I can still manually dim the screen. I also installed the Kenwood KNA-G510 navigation system and it won't dim automaticly or manually. The navigation screen is way too bright at night.

Pros:

Cons:

Metra GMOS-01 Wiring Interface

robert from Caldwell, ID on 4/11/2008

2008 GMC Canyon
Crutchfield Customer Review (What's this?)

Wow this was so easy to put in. Having the two volume controls is nice because my factory door tone was way to loud and I also toned down the Onstar voice, "Donna was just to loud"

Pros:

Cons:

A Big Box

Jeffrey from San Diego, CA on 3/5/2008

Crutchfield Customer Review (What's this?)

This unit is easy to install and hook up. It is however rather large and some may have to really work at getting this to fit way back in the dash panel. ADVICE- The sound adjustments are on the box. Test and adjust the chime and Onstar sound levels BEFORE you finish the install, unless you like removing your head unit.

Pros:

Cons:

DESPARATELY HAPPY

Anonymous from Clifton VA on 2/27/2008

Crutchfield Customer Review (What's this?)

I was crushed that there was no GM way to hook up. My son scanned and found the device. He had a list and I made the choice of you guys because I trust you. I do not even remember considering the price difference although my son tried to push "cheap" as a choice. I prefer trust. Most excellent to have both HD and OnStar. Thanks, guys.

Pros:

Cons:

Does what needs done

Josh from Columbus, OH on 8/17/2007

2007 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

Purchased the Metra GMOS-01 Aug 5th &amp; it was on my door step Aug 7th. Installed it Aug 8th and it works like a charm! <BR><BR>Easy, straight-forward installation, truely is &quot;plug n' play&quot;.<BR><BR>The reason I only give it 4 of 5 stars is that OnStar only gets 3 volume setting now and to adjust you have to be able to get to the unit (which is behind the HU in the dash). Also the door chimes are super loud but can be adjusted at the unit, again, BEHIND the HU in the dash.<BR><BR>All n' all, a GREAT product at a GREAT price!!

Pros:

Cons:

Metra GMOS-01 Wiring Interface

Rick from new windsor ny on 5/13/2007

2002 Chevrolet TrailBlazer
Crutchfield Customer Review (What's this?)

easy plug and play product....works well follow all instructions word by word and you wont have an issue.

Pros:

Cons:

Details

Hands-on research

Product Research

Features

Overview: The GMOS-01 lets you install an aftermarket receiver in select late model GM vehicles without losing the OnStar Emergency Services features or the chime that warns the door is open. Please check the Crutchfield Vehicle Selector to confirm compatibility with your vehicle.

Note: This adapter is not compatible with factory Bose or Monsoon systems.

Connections: The module includes a 10-pin harness (5 pins used) that connects to the switched power and front speaker leads of the new radio. A second harness (12-pin, 10 used) connects the module to the factory OnStar and radio plugs, plus the rest of the wiring for the new radio.

OEM Steering Wheel Control Compatible (optional): The GMOS-01 features a right-angle 3.5mm connector that lets you keep your GM vehicle's OEM steering wheel controls via the optional Axxess Steering Wheel Control Interface (120ASWC1, sold separately).

Volume: The volume is adjustable for both the OnStar output and the warning chime.

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team. They verify what’s in the box, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.

Q & A

Customer Q&A

Crutchfield asked  
Why did you buy this?

I chose this item because it signals my car aftermarket radio to turn on. my car did not have an ignition switched wire only 12v constant so I needed something to provide it with one. this item seems to do the trick. [ CAMERON  Aug 14, 2016 ]
Fits my colorado [ phillip  Aug 14, 2016 ]
Very easy to hook into existing wiring and keep all the safety chimes. [ CHRISTOPHER  Aug 11, 2016 ]
wanted to keep oem onstar [ Hans  Aug 10, 2016 ]
Needed for install [ Rick  Aug 08, 2016 ]
As much as I would like to eliminate that dinging when I leave my car door open, it reminds me to take my keys .... [ Dennis  Jul 26, 2016 ]
The Metra interface aloud me to retain my trucks features [ Lyndale  Jul 09, 2016 ]
retain OnStar service ! [ M  Jun 13, 2016 ]
told me to [ Blake  Jun 09, 2016 ]
I always look to Crutchfield...They are the easiest and most complete. Plus they are always only a phone call away for help! [ David  Jun 08, 2016 ]
suggested for new unit installation [ Gerald  May 20, 2016 ]
It was the right part for my application. Happy with purchase! [ Bobby  Mar 24, 2016 ]
well, it was not due to the price,, but, when you have to have it you just need to get the best [ eric  Mar 20, 2016 ]
A true must have to make for not only an easy install but to retain all your factory equipment. A must have for a professional install at home. [ David  Feb 28, 2016 ]
To ensure factory chime, warning s and on-star still function while I'm getting my jam on. [ Y  Feb 12, 2016 ]
so I can install my radio and drive my vehicle [ Daniel  Jan 31, 2016 ]
Came free with purchase of speakers [ Troy  Jan 17, 2016 ]
required to install [ Thomas  Dec 04, 2015 ]

7 questions already asked

You will want to contact an Advisor by phone (1-800-324-9695) or online chat to discuss compatibility with your factory system. They will be able to pull up your vehicle and see if this will integrate. If it does not, then they will also be able to discuss other options with you. [ Krissy  Sep 27, 2016 ]  Staff
You will want to contact an Advisor by phone (1-800-324-9695) or online chat to discuss compatibility with your factory system. They will be able to pull up your vehicle and see if this will integrate. If it does not, then they will also be able to discuss other options with you. [ Kenny  Jul 22, 2016 ]  Staff
You can check to see if this will fit your vehicle by using our Outfit My Car tool: http://www.crutchfield.com/car/carselector.aspx For additional details on fit or installation please contact an Advisor by phone (1-800-324-9695) or online chat. They will be able to pull up your vehicle and give you the details on if this will fit and what you will need for an installation in your vehicle. [ Kenny  Apr 29, 2016 ]  Staff
You can check to see if this will fit your vehicle by using our Outfit My Car tool: http://www.crutchfield.com/car/carselector.aspx For additional details on fit or installation please contact an Advisor by phone (1-800-324-9695) or online chat. They will be able to pull up your vehicle and give you the details on if this will fit and what you will need for an installation in your vehicle. [ Krissy  Mar 29, 2016 ]  Staff
You will want to contact an Advisor by phone (1-800-324-9695) or online chat to discuss compatibility with your factory system. They will be able to pull up your vehicle and see if this will integrate. If it does not, then they will also be able to discuss other options with you. [ Kenny  Jan 01, 2016 ]  Staff
If you purchased the product from Crutchfield, feel free to contact our Tech Support team. They can walk you through the settings on the product and see if there may be a fix. Our toll-free Tech Support number is printed on your invoice, and is also available under the "My Orders" tab in the "My Account" section of our website. If you did not purchase the unit from Crutchfield, then you may want to contact the manufacturer. You can also post your question in our forums: http://community.crutchfield.com. Or try our online support center: http://crutchfield.custhelp.com/app/answers/list/kw/. [ Krissy  Apr 18, 2015 ]  Staff
Though late in the game this is what I have learned and hope it benefits everyone. The module can be used with amps, BUT you must bypass the module of the amp power and get an additional speaker for the warning chimes (Metra SP-2003 sadly not found at Crutchfield). On my 2004 Chevy Colorado I tried using one of the tweeters that I removed (when I upgraded to components) for the chime but it was too quiet whether it was wired before or after the inline resistor. Metra has specific instructions for using this module with amps on page 7 of the owners manual. I do NOT have OnStar so have no idea how this would play in, but if you want your warning chimes on a NON-OnStar vehicle then it appears getting the Metra SP-2003 (or possibly any 12V speaker with a good volume level) appears to be the only route to take when using amps and the Metra GMOS-01. I plan on ordering the SP-2003 in the near future but for now this is the best I have to offer. I do not pretend to know everything, or anything, but this is what my research has come up with and hope it helps any one looking for the same answers I had about the "amp" situation. [ CycoStu  May 28, 2014 ]
Hi, I didn't added an amp to my car, but I'm using the module, I have a 2005 buick lacrosse equipped with on-star. This module helps you keep the door chimes sound for door opens, or seat bealt alerts. Also keeps a Connction going from the radio to the rear view visor that has the built-in Mic in order to talk to the on-star assistant. The radio I bought with this module has its own Mic which I use for phone calls using the Bluetooth service. Hope this information helps. [ RANSES A  Dec 31, 2013 ]
Hi Mike, This unit doesn't have line level inputs or outputs. Provided the unit can handle the additional power of the amplifier, you could hook it up post amp. The purpose of this unit is to allow the OnStar system to use your speakers for communications. If you are wiring head unit-amp-speaker and bypassing the factory wiring and you are not worried with your OnStar the you really don't need it. Hope this helps Will MECP certified installer [ WILLIAM  Dec 29, 2013 ]
Mike M, I installed this in a GMC Envoy XL using just the standard speakers. I believe the adapter was required for maintaining the OnStar capabilities thru the new head unit. Unfortunately I didn't add additional amplifiers like you are but I believe the wiring would still be similar to the diagrams provided. I probably didn't give you much help with my answer but I think you should try to keep the adapter in the setup. I wired and soldered everything before hand before I even went out to the car so everything plugged in nicely once I got started. Good luck! [ C S  Dec 28, 2013 ]
The wiring harness makes this much easier to splice into the factory system - I suppose you CAN do it without but you'll have a lot more heartache and virtually no complications this way. This helps you retain OnStar and the door chime which will both disappear if you do not use this. There is also a PAC unit for GM cars that also works but you do not retain OnStar or the chime - which is the route I went. I have a Hummer H3 and this was necessary as the car had an external amp for the separates and no subwoofer. I added a sub (JL Audio Stealthbox) and new amp to replace the factory amp and a whole new amp for the sub. [ ERIC T  Dec 28, 2013 ]
Library

Searches related to the Metra GMOS-01 Wiring Interface Connect a new car stereo and retain OnStar®, factory door chimes, and audible safety warnings in select GM vehicles