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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29427
Experience:  GM Grand Master Technician 2007. 14 years experience.
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GM carlo: 04 carlo, different pcm 5 yr,

Customer Question

04 monte carlo, different pcm for last 5 yr, need ign switch, then again in oct for the recall. Returned to stock including stock pcm, starts and runs 1sec stalls out, passlock issue, can not seem to get it to go into relearn
Submitted: 1 year ago.
Category: Chevy
Expert:  GM Tech (Cam) replied 1 year ago.
Hello, I'm Cam.
Can I get your first name please?
I will post the proper relearn sequence at the bottom, check that against what you are doing.
Also when you returned it to stock, was the pcm the original one or just a factory tune? I ask because we need to make sure the programming in the bcm matches the pcm in terms of the vin. If the pcm is programmed to one vin and the bcm a different vin, then it will never learn the theft system.
Turn the key on and attempt to start the car, It may crank, it may start and stall or it may do nothing at all, this is fine, still cycle the key to start then release the key back to run. Wait 10 minutes with the key in run. The passlock light should be flashing and the DIC will say "Service Vehicle" or "Security" or have a picture of a car with a lock during that 10 minute span. After 10 minutes has passed, turn off the car, count to 10, and try to start it again and release the key back to run. Wait another 10 minutes. After 10 minutes, turn car off 10 seconds and try to start again and release the key to run. Wait another 10 minutes. After 10 minutes, turn car off 10 seconds and try to start again. It should start up this time. The passlock has been learned. During this process, turn the fans off, radio off and cycle the headlights off so the battery will not go dead. If needed, use a battery charger.
Customer: replied 1 year ago.
It is the original pcm from the car and harness. Only things not original is the crank and cam sensor as short block are from a downer car, part numbers match and used my original short wire leads that connect to harness near ignition coils. The procedure you listed is one that I have tried but have deviated from slightly and not fully completed since when the car stalls and I leave it in the run position the security light dose not come on so I am unable to wait for it to go off. The light only comes on when you first move the key from off to run. I read somewhere you may need to delete and theft codes from the bcm for it to go in to the relearn mode, is this correct and can only a tec2 or snap on solas/modas turn off those codes?
Expert:  GM Tech (Cam) replied 1 year ago.
You could try a reset by removing both battery cables and touching the ends together for 10 seconds.
Customer: replied 1 year ago.
So tried the reset but no change, after turning the key to start and fall to run the secrity light did not come on, still only comes on when moved from off to run and will not shut off, I am doing this with window open doors and trunk closed. Tried doing the relearn by time even without the light on but no change. Only thought I have is one thing I read that said in order to go into a relearn there can not be any security codes set in the bcm, they must be cleared first. Dose this sound correct? If so I have a friend with a good scanner that can stop by and read the bcm. My scanner only reads pcm and only code I am picking up is rear o2 since I dont have the exhaust hooked up fully, waiting on gasket. Other than that no codes coming up on the pcm side.
Expert:  GM Tech (Cam) replied 1 year ago.
Ok, lets see what the full scanner shows.