BCM radio failure in '97 Firebird

[jasonp99]

Hi all. My '97 Firebird T/A's BCM has an intermittant failure in that the radio and power windows will lose power. I've removed the BCM from its holder and disconnected the J1 and J3 connectors. With the J2 connector (middle one, black) still connected and the key in the ACCY position the radio will work. But if I just apply some pressure to that connector I can get it to turn off or on at will so I'm pretty sure the problem is either in the connector or on the board at that spot.

Looking at the board I can't see any obvious solder cracks. Probing with a multimeter on the BCM I get about 1.1 kohms between pins D and A(gnd I think). Also pins D and C appear to be shorted (0 ohms). I don't have a schematic for the BCM circuit (found a '96 one but the '97 BCM is different).

I can get a used BCM (matched to my key resistor value) for about $100 off of eBay (from Trans Am Creations) but I'm not yet sure it's the board and not the connector going to the board. I inspected the metripak briefly and it appeared all 6 wires were going into the connector solidly.

Any clues?

[Rob B (shoebox)]

I would think the 96 and 97 BCM would be the same (schematic).

[jasonp99]

Possibly, but the BCM changed for '97 (same for '97-02) so that would imply the circuitry could have changed as well.

[Rob B (shoebox)]

You may be right. I don't have a 97 manual.

[Jeff_in_Atl]

FYI I was told the BCM has to be programmed to your car for the options it has. Another words if the BCM was on a car with manual windows and you put it in a car with power windows the power windows won't work.

[jasonp99]

FIXED!

I got my new BCM from eBay, it matched my key pellet and broadcast code (KUB). Installed it and now the windows and radio work fine, no intermittent cutoffs. My key fobs didn't work so I went through the reprogramming sequence and they work now.

When I had the original BCM in the car and the board exposed I was able to determine that when the radio turned off the voltage on pin D of connector C2 (possibly the input from the ignition switch) switched from 12V to 0V. The original connector works fine in the new BCM so the open circuit must have been in the original BCM.

On an un-related note the new BCM didn't clear out the security light (which has been on for over a year). I found a description to read the BCM codes out so I might try that:

http://shbox.com/1/4th_gen_tech2.html#bcm