Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
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 ?
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
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.