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Axxess GMOS-LAN-04 Wiring Interface

Connect a new car stereo and retain OnStar®, safety warning chimes, and factory amplifier in select 2006-up GM vehicles

Item #: 120OSLAN04

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The Axxess GMOS-LAN-04 GM radio replacement interface lets you replace the factory radio in select OnStar-equipped 2006-up GM vehicles using the existing wiring and connectors. Even if you don't subscribe to OnStar, you'll need this adapter to connect an aftermarket stereo.

Connect the GMOS-LAN-04 to your aftermarket radio, mount the module, and plug it into the existing factory plug. Get the great sound you want, and keep all of the important safety features intact.

You can adjust volume settings for OnStar as well as the safety chimes. In addition, this interface lets your new receiver work with your vehicle's factory amplifiers. This interface gives you convenient plug-in connections for the Axxess steering wheel control adapter (not included) that works with most aftermarket stereos – that means less wiring work for you.

This interface works with select 2006-and up General Motors 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: 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.

Axxess GMOS-LAN-04 Wiring Interface Reviews

Average Customer Review:

11 Reviews

for 2011 hhr premium sound system

Written by: Mark from Pekin, IL on January 29, 2016

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

Fairly straight forward to install, did have some issues with the harness not being compatible with the steering wheel control module

Pros: Easy to install Retained most chimes and waning bells Volume feature for the radio and bells worked great

Cons: Had to rewire some of the connections to get the steering wheel controls to work properly Lost my turn signal and hazards sounds


Written by: Augie from deltona, FL on January 24, 2016

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

is easy to install , nice plug and play and it works the first time .

Pros: plug and play , good quality

Cons: the price is a little high but he works good .

Awesome wiring harness

Written by: Anonymous from Warner Robins, GA on May 13, 2015

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

Amazingly easy to install




Written by: The SWAG Tech from Raleigh, North Carolina on April 28, 2015

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

Colored wires matched, quick and simple install. All factory items still work.

Pros: Everything

Cons: None

Access GMOS-LAN- 04

Written by: Mr Keith from Florida on March 5, 2015

Crutchfield Customer Review (What's this?)

I used it in my Malibu 2009 LTZ. I installed a Pioneer AVIC-120bt. Easy hook up. No Problems at all. I still have OnStar. All factory chimes

Pros: Plug & Play

Cons: None

Room for improvement

Written by: RP from Daphne, AL on July 23, 2014

Crutchfield Customer Review (What's this?)

A must if you want to easily keep On star, and warning chimes on an aftermarket HU. The blinker tone should have been built in instead of using a bulky relay to make the clicking sound. It serves the purpose, but is overpriced in my opinion for what you are getting.

Pros: Lets you keep warning chimes and On star

Cons: Relay used foe the blinker sound takes up precious space

easy to install

Written by: Antonio from san Diego, ca on January 7, 2014

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

Does its job. Keeps the chimes active with out the stock receiver



Adapter review

Written by: Ben R. from Columbia, MS on March 22, 2013

2009 Saturn Aura
Crutchfield Customer Review (What's this?)

Works great.

Pros: Everything works fine.

Cons: Nothing.

Bad impedance match???

Written by: Joacchim from Chagrin Falls, OH on February 4, 2012

Would not permit higher volume levels from my wife's 2008 Chevy Malibu without significant distortion, even after swapping out original unit with another Crutchfield-supplied unit. Pretty sure the radio's not at fault, it works at lower levels.

Review revised 5/9/12
After much troubleshooting and pulling-out-of-hair, culminating in an "aha!" conversation with Crutchfield tech support, discovered that my wife's car radio does not incorporate an external audio amp. Therefore, this interface would not work. Crutchfield promptly shipped the correct interface (GMOS-LAN-03) which worked as advertised.

Pros: Can't think of anything positive to say except that I could be wrong about this product.

Cons: There's a zillion wires you have to get to fit under the dash. Case does not allow one of the plugs to go in without trimming the plastic - the opening didn't allow space for the locking tab on the wire plug-in. As mentioned, apparently not a good impedance match between OEM internal amp and aftermarket radio.

Almost Flawless

Written by: EricJ from Battle Ground, WA on February 8, 2011

2007 Saturn Sky
Crutchfield Customer Review (What's this?)

The only place where I will agree with the previous rater is that this device
does not allow aftermarket amps to be used.

Blame GM for their audio design, not Metra for their adaptation. If you are
dead-set on aftermarket amps, speakers, and head unit, then you need to be
prepared to give up the factory XM, OnStar, and warning chimes, or to do a lot
of work to re-engineer the GM system. This issue is not unique to GM vehicles -
many modern automobiles have highly integrated audio systems and it is getting
much more difficult to install aftermarket equipment!

I used this interface to replace my Monsoon (Panasonic) radio that had failed
buttons, with a JVC unit, in my 2007 Saturn Sky. It worked almost flawlessly.

The one issue: if you like leaving your key in the ignition with the door open,
the chime WILL time out, unlike the factory setup. I will have to remember to
take my key out when I am fueling my car....



Axxess GMOS-LAN-04 Wiring Interface

Written by: Gilberto from Laredo, TX on November 22, 2008

This unit will only work if you replace your stereo, and still use your original speaker setup, amp'd by the stereo.

If you try to use an external amp, you'll loose all the features of this interface, and it will become worthless.

Read a lot and get clear of what will your setup be.



Hands-on research

What's in the box?

Download owner's manual

  • GMOS-LAN-04 Module
  • 16-pin harness
  • 18-pin harness
  • Installation instructions

Product Research


Overview: The GMOS-LAN-04 is designed to retain the amplified sound system, Onstar's emergency services function, and the warning chimes that are normally lost when the OEM radio is removed and an aftermarket radio is installed in select GM vehicles. It also provides a 12 volt accessory output for proper aftermarket radio operation. In addition, the GMOS-LAN-04 provides a mute, parking brake, VSS or speed sense, and a reverse output to make installing an aftermarket navigation radio simpler and less time consuming.

Compatibility:The GMOS-LAN-04 is compatible with the following GM vehicles:

  • Chevrolet:
    • 2006-2010 Cobalt
    • 2006-up HHR
    • 2008-up Malibu
  • Pontiac:
    • 2007-2008 G5
    • 2009 G6
    • 2006-2009 Solstice
  • Saturn:
    • 2006-2009 Aura
    • 2006-2009 Sky

Volume Adjustment: The GMOS-LAN-04 interface features potentiometer located on the 16 pin harness side of the module to adjust the volume, including chime and audible turn signal indicator volume.

OEM Steering Wheel Control Compatible (optional): The GMOS-LAN-04 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 (item number 120ASWC1, sold separately).

Connections: The GMOS-LAN-04 consists of a single interface with a 16-pin connector on one end and an 18-pin connector on the other end, along with the corresponding harnesses. The 16-pin harness plugs into the interface and is hardwired to your new radio's harness. The 18-pin harness plugs into the interface and three OEM harnesses behind the radio. The 18-pin harness also has several leads to hardwire to the new radio.

Installation Note: The GMOS-LAN-04 uses the existing factory amp to send the audio from the OnStar, door chime and turn signal sound to the left front speaker of your vehicle. So you will need to retain at least the front channels of your factory amp to utilize this interface.

Optional RSE Retention Harness: The Metra GMRSAV (120GMRSAV, sold separately) is an RSE retention harness designed to retain the rear seat entertainment system in these select GM vehicles. The GMRSAV provides an audio/video input to the factory overhead video screen from your new aftermarket radio, and provides the audio/video output from the rear seat control panel to the aftermarket head unit.

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.

Customer Q&A

Crutchfield asked  
Why did you buy this?

Without this my chimes would not work with my new radio. [ Bryan  Dec 15, 2015 ]
because its what i need and the price is reasonable [ Randall  Dec 07, 2015 ]

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