PCM reprogramming

[diazepam]

I have a 99 Grand Am SE (3.4L) and have a problem w/ the PCM ... it does not "turn on" the generator. If I swap out the PCM, do I need to have it reprogrammed by the dealership (my mechanic says no - according to his OnDemand software - but the dealership and salvage yard, where I was going to buy from, says "maybe" and "yes" respectively ...) Also, is there a difference between ECM and PCM? or are they the same part?

Thanks!

[catback23]

If you have factory security system then definitely yes you are going to have to program the new ECM/PCM. Otherwise as long as it is for the same model/year/engine/transmission I'd say it doesn't need reprogramming. As for difference between ECM and PCM, ECM stands for Engine Control Module and PCM stands for Powertrain Control Module. You can by the name tell what each does with powertrain being basically another way to say drivetrain. There are two different systems but the catch is why have two individual control modules when you can just combine them into one box and just call it a ECM/PCM or just PCM. And they do so your PCM is both a ECM and PCM all in one box.

[diazepam]

thanks, i had forgotten about that "security" system - i guess that makes sense.

[diazepam]

ok ... so my mechanic has been reading his OnDemand software concerning PCM replacement in my car. it says that you change the EPROM (from the old PCM to the "new" ... or in my case, used) and install. the car will not start the first time, wait 15 minutes, then the car will start? sounds like something with that stupid PASSLOCK system to me. can anybody confirm this?

thanks!

[catback23]

Yea that's passlock reprogramming.

[diazepam]

Originally Posted by catback23

Yea that's passlock reprogramming.

thanks for the help! :o)