Maslo

I bought my 2006 Z06 with a Kenwood DNX6990HD head unit with a GMOS-04. It has Bose, I don't know if my car has Onstar, and it does not have steering wheel controls.

I had a few gripes: white noise at all volumes, chime volume would reset to max on battery disconnect, and illumination function did not work (this was installer's fault, read below).

I had two options: remove GMOS entirely to clean up all the spaghetti wiring or simply bypass the GMOS with the audio wires only. Here's the key: the stock Bose amp will work without an interface. It needs to be given a signal to turn on, just like a subwoofer amp, and it likes preamp signals, but nothing special otherwise.

I chose to eliminate the GMOS-04 altogether, however this removes Retained Accessory Power (RAP). RAP enables the head unit used to stay powered until the engine is cut and then the driver door opened. Losing RAP means the head unit loses power right when you turn the engine off. Would be nice to still have that, but removing all that cluttered wire outweighed the RAP to me.

For rewiring, make sure you have your soldering iron, heat shrink, some RCA cables to cut into, some T-tap connectors to tap into existing wiring, and a fuse tap adapter.

Rewiring is basically matching wire colors, and like a hundred other threads cover this is good detail. I didn't document this very well, so I don't have very good pictures. Sorry if I'm letting you down here. Note that the Bose head unit produces white noise if given already amped signals (4V or higher I'm told), so cut up 2 pairs of white/red RCA cables to pull from the head unit preamps.

Also, the following few signals are special:

1) Switched +12V (ignition) must be pulled from a switched 12V line. There are several options, but I ran it up from the windshield wiper motor fuse seen here:



2) Illumination (dash light) is pulled from the Traction Control / Active Handling's grey/black wire with a T-tap.

3) My Kenwood DNX6990HD had a microphone mute wire. I connected this to the car's harness, however this must be intended to be a switch or something. I had to cut it, then everything works fine.

It may be all in my head, but the speakers seem to be a bit more clear than when going through the GMOS-04. It's not like a night and day difference though. Most importantly, those dang chimes won't deafen me any more.

TorchRedFred

Or you could of just purchased the correct wiring harness. The point of the wiring harness is that you don't have to cut into and splice into the cars electrical. You attach the wiring harness to the radio and plug it into the car without cutting anything. When looking at cars, I typically avoid buying cars where the previous owners cut into the electrical as it makes troubleshooting any potential future problems, or ever changing the head unit again, a nightmare. Also, just for the record the mute wire is for your head unit to be compatible with OnStar. When connected correctly, it mutes the radio when OnStar comes on.

Maslo

I created this thread to confirm that an aftermarket head unit would send power through a Bose stock amplifier to the speakers. I could not find anywhere on the forum stating this.

Also, unless I missed this fact multiple times, my car's wiring harness offers neither switched +12V nor dash light / illumination connections.

I hate cutting my car apart, but if I must to fix something that I didn't break in the first place, I think that's a step forward. Don't worry TorchRedFred, I won't be upset if you don't want to buy my nightmarish car.

TorchRedFred

Sorry if my post came across as strongly worded. I've just seen this done wrong more often than I've seen it done right. I was guilty of it myself once when I was in teens, and that's why I never recommend anyone to do it that way. I know there are better options than the GMOS harness, especially if you have the Bose system. The Pac Audio harness did seem to address a lot of the concerns you had and that's why I tried to steer you towards using it. I do remember connecting the dash light/illumination wire and also the chime module had a volume **** on it to adjust volume setting. And I didn't mean to imply that your car was a nightmare, only that troubleshooting potential future problems could turn into a nightmare for a future owner who would be unfamiliar with changes you made. It's all good though, glad you figured it all out.

Maslo

TorchRedFred, I replied very defensively and appreciate your level headed follow up reply. Thank you for your help, and I may eventually check out the Pac. I think we both agree that the GMOS-04 is the true nightmare.

TorchRedFred

No offense taken. My big mouth has a long history of unintentionally pissing people off, so no worries. If your set up is working good, I would leave it as is. My only concern was recommending to others to do the same when there skill set may be less than adequate. For most, a wiring harness is just cleaner and safer.