pcmhacking.net

. I have a question that I’m hoping someone can solve.. if I switch out the BCM will turning off vats allow the car to start? This is 2004 Grand Am GT. I read that some BCM’s can only be reprogrammed if their virgin ones and or the only way is take the Eeprom chip off and program it that way. I’m unsure if the VAT system is solely contained inside this BCM because I have two PCMS my old one and the one that’s in the car.
My old BCM took crap on me so the car wouldn't start. So I had to get the matching PCM out of the junk yard and the guy told me it was from a GT but I just found out it’s from an SE and and I really want to use my GT BCM but this BCM. It's really holding me back since the car won’t start with this new BCM in it if my original pcm is in it. My other option is to change the vin on my old pcm and that should fix everything and turn off vats/passlock??? Or I could swap the eeprom chips on my old bcm to the new(scary tho)

I doubt the vin change will work, that’s not typically how vats works, is more like a password is shared.

Can you not do a factory vats learn? Isn’t that a simple procedure with a tech 2? I can’t see a 2004 having a very complex system.

I think these posts from DethRattles got sorted. In one of them he was able to get obd-xpro and re-write his P04, and after a bit of discussion between members we found the right settings to disable vats in the PCM which solved his problem. We ended up with a number of unanswered threads like this one about the same topic, though.

See result here: viewtopic.php?f=36&t=8176&p=122197#p122197

Thanks antus we can always rely on you to keep track of things:)