30th droptop

iTrader: (-1)

Hi. I posted this under General Maintenance and Repairs and haven't gotten anything, so I thought I'd try it here:

I went to diagnose what I thought was going to be a simple problem - my courtesy lights weren't coming on. I went through the troubleshooting procedures in the factory manual, and it said my Body Control Module was bad. I looked it up on GM Parts Direct: about $150 by the time shipping is factored in. That's a lot of money just to get my courtesy lights working. Does anyone know where a BCM can be had at a better price? It's part number 09353691. My local junkyards don't have anything. Thanks.

MikeFbody

iTrader: (2)

if it truly is a faulty BCM, you have to buy it new. Once a BCM is "married" to a car, it cannot be swapped into another one.

Well, that's not entirely true. The issue is with the VAT System, the resistor chip in your key. The BCM actually handles that too, and when they are new from the factory, they learn the value of your key as the correct one, and there is no way to reset it. When installing a used BCM, you either need to bypass your VAT system completely, or take a 1 in 15 chance of it working (as there are 15 different key chip values).

what exactly is the problem with the courtesy lights ? what steps did you go through to troubleshoot ?

mike

jimmy 2 Times

iTrader: (18)

if you want to do the VAT's bypass (like you would if you add remote start) I have the BCM out of my car. I can meter my key to tell you the chip value. Shoot me a PM

30th droptop

iTrader: (-1)

The problem with the courtesy lights is that they don't work - either when the door is opened or on the dimmer switch. The map lights and glove-box light work fine, but only from the switches. I got BCM Trouble Codes 22/32 (courtesy light return to BCM shorted to B+). According to the factory manual, the BCM will shut down this courtesy light circuit when code 22/32 is/are set. So I followed the troubleshooting procedure in the FSM and verified no battery voltage in the return circuit. I cleared the codes, and they immediately set again. The FSM says those conditions mean a bad BCM (which makes sense to me).

That sucks that you can't just replace with a used BCM. I guess disabling the VATS would be an answer, if I knew how. I'll PM you. Thanks

dragonrage

Actually, you could use a resistor to change the VATS value, as long as you knew what it was compared to yours... If the new BCM wanted higher resistance, you just put the difference in series. If it wanted lower, you have to solve the equation:

Rtotal = 1/(1/Rold + 1/Rparallel) for Rparallel, where Rtotal is the resistance the new BCM wants, and Rold is the resistance the old BCM wanted, and put that resistor in parallel.

Or you could just get a new key made...

WhiteBird00

iTrader: (4)

That's a good suggestion...your best solution might be to take jimmy 2 times up on his offer and then just get a new key made that has the same resistor as his does. The problem with buying a used BCM is that you usually don't know what resistor value it was matched to, so you have to bypass the VATS. In this case you would know the correct value so you can just get a key cut that matches.

Mark A. Rogalski

iTrader: (1)

Mine is the exact same way!

Had it in the dealership this morning. They wanted $400. It's worth the $150 to me to have the lights work correctly and acces to turn on the back seat lights and dome at night for this convertible.