I am seriously researching what is needed to reuse my existing Head Unit in a '09 C6 w U65 (built in changer, no nav, steering wheel controls (UK3)). I have the PAC ADD-GM24, OEM-1 and PAC-RCA adapters to interface to new amps (one for speakers and one for sub). I am current planning on completely bypassing the Bose amp and reusing the space for component cross-overs and possible speaker wiring.

I am looking at page 8-8 of the '09 Y-car service manual and there are three wires from the head unit to the Bose amp that I can only guess what they are. It looks like they are switched grounds from plug pins X1-B6, X2-B and X1-B3 (OG, GY and WH colored wires). I am thinking they are something to do with muting and/or power connected to the cell phone, Bluetooth and nav systems.

What could be a deal killer is if I loose the radio mute while on the phone or getting DIS messages but surely bypassing the Bose amp would not do that, would it?

I appreciate any and all constructive comments about my plans so far and suggestions to do something different or better.

 

you will lose nothing, what pac to rca adapter do you have?

well u could have issues with radio mute and cellphone

 

For anyone else who cares to follow along, the schematics and plug pinouts are available if you click here

The orange wire at C1-B6 looks like it sends a signal to the amp telling it to mute. I've never messed with that, but I'd guess that it either generates or removes either a 5V or 12V signal when it wants to mute. Hook everything else up and see what happens first, you may get lucky, but worst case you'd just have to install a relay (of the proper type, NO vs NC and 5V vs 12V) using that orange wire on the coil side and having the amp trigger wire on the contacts.

The grey wire at C2-B is what controls the speed sensitive volume controls. Looks like you're gonna loose that with an aftermarket amp, but who cares.

The white wire at C1-B3 is the wire that you need to use as the 'switched' +12V trigger wire for your new amp. Just splice into it somehow since it needs to stay connected to the antennas and such. If you're removing the OEM amp it obviously won't be coming on and causing problems.

Other random thoughts.....

I didn't look at the adapters you have listed, but other than the white C1-B3 trigger wire, the only other wires you need to worry about coming FROM the HU are the line-level audio outputs going to the new amp.

C1 must stay connected to the HU. If you end up cutting wires or adding another jumper harness, make sure pins A6 and A7 are still connected or passed through. They are the two wires that connect the HU to the steering wheel controls.

Questions?

 

agreed worst case u add a relay, where does the oem bluetooth pipe its audio through

 

No idea, but the onstar schematic has it's audio signal going back into the radio, so I'd assume it comes out of the regular speakers after going through whatever amp is connected, just like onstar.

 

yeah i would think the same thing, i wonder why the seperate mute wire then, but i agree i would say 99% you will have zero issues

i also recommend wiring a peripheral sven4 inline its got noise filters in it and its not a bad idea as some ppl get alt whine

 

That is kinda what I figured. I just can't for the life of me wonder why they would do that since I thought they use the front speakers for chimes, messages, phone, etc. so what is the point of muting the amp? Come to think of it the HU itself does not have a mute button. The only way I have found to mute the HU is to push the Bluetooth button on the steering wheel but the Bluetooth seems to come in the HU so I dunno!


This option uses a mic under the steering wheel and acts (apparently) directly on the amp so that is lost for sure! It never seemed to work to me anyway. I never noticed any volume changes and often had to adjust it manually when I got up to cruising speed. So that is no lost.

Good point! I can do that, probably just leaving that part of the amp plug alone would do that.



The PAC GM-24 is direct pass through between the socket to the HU and the wiring harness plug; it has a tee-off for the low level speaker outputs (RF/LF/RR/LR) and an amp trigger wire. That plugs into the PAC-OEM-1 which is a tranformed and balanced isolating interface to the PAC-RCA which is just the four RCAs with the amp trigger passing through to the PAC-RCA. With the exception of having to splice in the amp trigger somewhere, it looks to be all plug and play. In theory you could keep the Bose Amp and speakers and run a new system in parallel.



Excellent point and I making a note of that, right now.

Thanks bunches!

 

i think earlier c6's also had that mute wire and it just told the amp to mute while changing sources or something esentially useless and wont effect anything, i could also be wrong