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Gary
Gary, Chevy Technician
Category: Chevy
Satisfied Customers: 15702
Experience:  15 years GM master tech
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I just replaced my ecm and it won't start

Customer Question

I just replaced my ecm and it won't start
Submitted: 1 year ago.
Category: Chevy
Expert:  Gary replied 1 year ago.

I am sorry your having this problem

was the new ECM programmed to the trucks VIN number before it was installed or programmed after it was installed into the truck ?

Customer: replied 1 year ago.
According to Oriely's before I picked it up
Expert:  Gary replied 1 year ago.

if it was preprogrammed after it was installed did you perform the theft relearn ?

if not and it was programmed correctly from them the only thing left to do is to follow this here and it should take 30 minutes to perform the theft relearn

if after the theft relearn it will will not start and it did start with the old ECM then either it was not programmed correctly from them or it is defective once programmed and installed and the theft relearn performed it should run

  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to start the engine, then release the key to ON, vehicle will not start.
  3. Observe the SECURITY telltale, after approximately 10 minutes the telltale will turn OFF.
  4. Turn OFF the ignition, and wait 5 seconds .
  5. Repeat steps 1 through 4 two more times for a total of 3 cycles/30 minutes , the vehicle is now ready to relearn the PASSLOCK(TM) Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK.

IMPORTANT: The vehicle learns the PASSLOCK(TM) Sensor Data Code and/or password ***** the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.