kostya_f

I have the same problem of no courtesy lights. I tracked it down to the BCM not providing a path to ground. It looks like there is a resistor in series with the fet that pulls that D1 pin to ground and mine is definitely out of the range I'd expect. Also on my BCM there was melted plastic behind the fet with a heatsink resting against the plastic housing.

Could someone measure the value of the resistor in this picture?

chobes

iTrader: (18)

I have the same problem, and know for a fact that it's the BCM. I have a replacement BCM that is going into the car, and then a buddy of mine who is really good with electronics is going to try track down the issue on the BCM board. I'll update this post when I get some results....

Kostya_F: If you get an answer on the resistor value, please post it here.

Topless TA

iTrader: (10)

yes please do, id like to try that the bcm was soldered and locks etc work better but still no int lights

chobes

iTrader: (18)

Back to square one. I picked up a BCM from one of the local junkyards and the GM dealership wasn't able to program it to my car, claiming that the BCM is "locked" to the car it was originally installed in.

Time for some more research into the BCM....

WhiteBird00

iTrader: (4)

Your dealer is partly right but mostly wrong. The only vehicle specific programming in the BCM is the VATS code. Once a new BCM has been matched to a particular resistance value from the original ignition key, it cannot be reprogrammed to a different value.

However, everything else will work so it would be worthwhile to plug it in and see if it solves your lighting problem. Then it just becomes a matter of finding which of the 14 resistor values matches the used BCM's programming and getting a matching key made (or doing a VATS bypass). You can buy a kit that allows you to select each resistance value without having to solder together a bunch of individual resistors for each possible combination. For that matter, you've got a 1 in 14 chance that your existing key will already have the right resistor.

Oh, and before somebody tries to correct me that there are 15 VATS values - GM produced 15 different VATS key combinations but only 14 of them were ever used in F-bodies.

Topless TA

iTrader: (10)

Can measure the value of the resistor in the picture above?

thanks in advance

chobes

iTrader: (18)

WhiteBird, thanks for the input. I've checked the "new" bcm and the lights work perfectly, time to look into one of those resistor kits.

TTa - I don't have any tools to measure that resistor value, am trying to get a buddy to do that for me this weekend.

Topless TA

iTrader: (10)

thanks big time in advance

chobes

iTrader: (18)

I'm not much for electronics, but I did find an ohm meter in the garage.

Correct me if I'm wrong, but won't the ohm meter give a false reading when the resistor is already attached to the circuit?

vertie

Courtesy lamp failure? Especially if you have a convertible that has 5 lamps instead of 3 like a t-top car has. My lamps quit whether you open the door or use the dash switch. If this happens, it's most likely the ground side circuit of the BCM module. Inside your module you will find a transistor with a heat sink (the only one in there with a heat sink). It's actually an FET made by international Rectifier rated at 8 amps. Replace it with a BUZ71A FET rated at 13 amps. I've replaced two of them in two different cars so far, and so far, so good! They cost about two dollars and not two hundred dollars like a new BCM costs,that you have to program! You will need to unsolder your old transistor and solder the new one in so if you can't do it, find someone who can. It's a CHEAP fix! Best wishes, Vertie

Topless TA

iTrader: (10)

very cool ill have to try this
thanks!

CO99Z28Vert

iTrader: (30)

Ok so is this the one I need before I order it? http://www.ebay.com/itm/Harris-Semic...450#vi-content

Thanks for the help!