Can someone please post or email me a copy of the C5 wiring diagram. I am trying to install a radio and can't find where to hook up the wire for illumination.

 

Obviously you have never seen a C5 service manual. It has a VERY complicated collection of interconnected modules. I will give you the info I have posted before.

The C5 stereo does not use the standard pinout that is in most older GM cars. Most installers have no clue on the wiring of the C5. The HU is connected to the car DLC serial data buss. It gets various control messages sent to it from the BCM and PCM like power ON/OFF, illumination changes, car speed changes ...etc..
You DO NOT want to connect to wires in the HU harness you are unsure of. Only use the 8 speaker connections, unswitched power and ground. Other connections are not to be used.

1. The HU does not get a switched power input from the car. The BCM commands it on. The HU then outputs switched power to turn on the stereo modules. You must find a switched power point to tap and add a power relay for a high power deck.

2. Unfortunately you will have to tie your illumination input to +12 and leave it fixed. The HU is not connected to the car dash illumination. The BCM commands the HU for illumination changes. The dash illumination is driven by the BCM which uses a technique called PWM to vary brightness. The bulbs are connected to +12 volts and then the BCM "pulses" them to ground.

Signal CD/Radio connection

Power C1(10) ORG
ground C1(5) BLK/WHT

RF+ C1(4) DK GRN
RF- C1(3) LT GRN

LF+ C1(2) TAN
LF- C1(1) GRY

RR+ C2(18) DK BLU
RR- C2(17) LT BLU

LR+ C2(20) BRN
LR- C2(19) YEL

 

99HT,

Thanks for the info. I have a adapter kit from soundgate made for the C5. Everything is pretty straight forward. The only thing they did not cover was the illumination. So, do I hook this up to a constant 12v or a switched 12v?

 

It depends if the wire goes directly to bulbs in your new HU or to a circuit that controls the bulbs. Connect the wire to whatever switched power connection you are using.

 

Try the yellow lead going into your HVAC head as I posted in the other section. You will be pleased!

 

I looked at the HVAC bulb and it seems to be one of the few illumination bulbs that is grounded at one end. The bulb is fed a +12 volt PWM pulsed signal. It should work if your new HU can average the PWM signal to a constant DC level.

 

nevermind, that's not going to help very much

:seeya Jeff

[Modified by vmspionage, 8:25 PM 12/12/2001]


[Modified by vmspionage, 8:27 PM 12/12/2001]