Metra's GMOS-06 wiring interface lets you replace the factory radio in select 1996-05 Cadillac vehicles with premium or Bose® audio systems, while retaining use of OnStar, all factory warning chimes, and audible turn signal indicators. Even if you don't subscribe to OnStar, you'll need this interface to connect an aftermarket stereo. The interface includes navigation outputs, so you can install an in-dash navigation receiver. Warranty: 1 year.

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

Metra GMOS-06 Wiring Interface Reviews

Average Customer Review:

13 reviews
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Seem to have issues

Written By salkomike, Stp,mn on Thursday, May 22, 2014

It has this low pitched ringing sound when i open door and sit in it. u hear it not during music cause im bumping and it'll be bumping. the volumes starts normal then goes down. help gimmie my cash back

Pros: No

Cons: No

Crutchfield response on Tuesday, May 27, 2014 We forwarded this review to our Technical Support team for follow-up. Lifetime tech support comes with every Crutchfield purchase.

Metra GMOS-06 Wiring Interface

Written By don w, center harbor,nh on Saturday, May 17, 2014

Crutchfield Customer Review (What's this?)

good fit,In my opinion it saved 8 hours of manual wiring,unless a professional


Written By Brandon, Dalton ga on Sunday, May 11, 2014

Crutchfield Customer Review (What's this?)

I hate this it doesn't beep now and it doesn't work right !

Crutchfield response on Wednesday, May 14, 2014 We forwarded this review to our Technical Support team for follow-up. Lifetime tech support comes with every Crutchfield purchase.

Kenwood Rocks my 2001 Cadillac DeVille

Written By Ed, Pittsburgh, PA on Wednesday, October 16, 2013

Installed this with a Kenwood head unit and the steering wheel control unit. The only issue is the warning chimes on the backup collision detection is not as good as the factory, very difficult to hear. The unit does retain the power to the unit until the car door is open with the key removed, like the factory installation

Pros: Retained factory features of the Bose system

Cons: Chimes are muted and the unit is large. Between the head unit the steering wheel unit and this unit, I had to double back tape the last two items to the top of the stereo cutout to get everything to fit.

Crutchfield response on Wednesday, October 23, 2013 Thanks for your review. The interface has a potentiometer that allows you to adjust the input level going to the factory amplifier. This potentiometer also adjusts the chime volume at the same time.

Loved it

Written By Al P, Ohio on Monday, July 15, 2013

Crutchfield Customer Review (What's this?)

Made things so much easier. No cutting into the factory harness.

Pros: Has a plug for the Axxess aswc-1 steering wheel controler

GMOS - 06

Written By Anonymous, Fredericksubrg, VA on Friday, May 17, 2013

No issue with install or function


Written By brad, chesterfield va on Monday, May 13, 2013

Crutchfield Customer Review (What's this?)

works perfect!

Review for the Metra GMOS-06 Cadillac Factory Integration Adapter

Written By Jaime G, Irving Texas on Thursday, May 02, 2013

Crutchfield Customer Review (What's this?)

Necessary connector.


Written By lsahnow, palmyra va on Monday, April 22, 2013

The adapter does what its supposed to do. The install was on a 2000 Cadillac Deville and coupled with the head unit I bought it was a very difficult install . there was barely enough room for the bulky OnStar retainer and miles of wires but in essence it did work and with time and patience was completed.

Pros: the product does what its supposed to do

Cons: miles of wires plugs and a bulky box to re-route because there isn't enough room in the head unit compartment for it all

Made for Cadillacs

Written By 0nurneez, Goodyear, AZ on Friday, March 29, 2013

Crutchfield Customer Review (What's this?)

This adapter works with a Cadillac perfectly. Installation was a breeze and Onstar, the door chime, and memory package are retained using this adapter. Simply wire it up to your aftermarket stereo and plug into your cars factory harness. No cutting of your cars wiring whatsoever. Perfect for people who like the Cadillac features and don't want to cut the factory wiring.

Pros: Easy to install and retains all chimes and Onstar.

Cons: A little bulky for tight spots.

Metra GMOS-06 Wiring Interface

Written By GK, Londonderry, NH on Sunday, February 17, 2013

This adapter was very difficult to match up with the old wiring. I don't have Onstar in my car, but, this was the only adapter that supposedly matched my new stereo with my old wiring. After connecting the adapter/harness the way I thought it was supposed to be connected (according to the instructions), I am experiencing all kinds of problems. The speakers don't work, the dash lights no longer work, and the battery dies for no reason. I have to disconnect the negative wire and reconnect it to re-engage the electrical system. I did not find this to be an easy replacement at all.


Written By Scott, Charlotte, NC on Tuesday, December 18, 2012

Crutchfield Customer Review (What's this?)

I had read on some of the Cadillac forums nightmares about trying to upgrade the factory Bose system. I was nervous about doing this install myself on my 2000 Cadillac Eldorado ETC . But this made the installation of my Kenwood DNX6990HD painless.

Pros: Easy install good instructions

Cons: The size of the unit I had a hard time finding a home for it.

Metra GMOS-06 Wiring Interface

Written By Ryan, Georgia on Wednesday, June 01, 2011

Crutchfield Customer Review (What's this?)

It works but its not the easiest to fit/hide. It works as advertised but it would be nice if it can more compact. Used this on a 2004 Cadillac Deville with a single din Kenwood receiver. There is no way to place the box on the top, side, bottom areas of the receiver. I had to place the box to the left of the receiver in the dash. This was the most time consuming part of the install.

Hands-on research

What's in the box?

Download owner's manual

  • GMOS-06 Cadillac OnStar Class II Data Bus interface
  • Wiring harness with 2" wide 32-pin blue plug on one end and a 1-3/8" wide 16-pin white plug on the other end
  • LD-NAVAMP harness with 1-1/4" wide (14-pin) plug on one end and speaker wire on the other end
  • Installation instructions

Product Research


Overview: The Metra/Axxess GMOS-06 is designed to interface an aftermarket stereo with the factory amplified audio system (including Bose) in select Cadillac vehicles with OnStar. It will retain the warning chimes that are lost when the factory radio is removed. The interface also provides a 12-volt switched accessory output, along with Mute, Parking Brake, Speed Sense (VSS) and Reverse outputs to allow you to install an aftermarket radio with navigation.

Compatibility: The GMOS-06 is compatible with the following Cadillac vehicles:

  • 1999-2005 Deville
  • 1999-2002 Eldorado
  • 1999-2004 Seville
  • 1997-2001 Catera (navigation outputs not available)

Level Adjustments: During the installation process, you can set the volume level of the OnStar voice commands. If the aftermarket radio has a high pre-out voltage, the audio signal may become distorted. The interface has a potentiometer that allows you to adjust the input level going to the factory amplifier. This potentiometer also adjusts the chime volume at the same time.

Retained Accessory Power (R.A.P.): The ignition power source of the Cadillac keeps the radio on until one of the doors is opened. This feature is called the R.A.P. (retained accessory power). The GMOS-06 is designed to retain this feature.

OEM Steering Wheel Control Compatible (optional): The GMOS-06 features a 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).

Note: The GM vehicle must have factory steering wheel controls to retain access to the factory customization menu, once the factory radio is replaced with an 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.