For 1990-2009 cars

In order for a theft deterrent vehicle to run, a password is communicated between the Body Control Module (BCM) and the Powertrain Control Module (PCM). If a PCM is replaced, the new PCM needs to learn the correct password for the vehicle. When the new PCM is installed, the EEPROM calibration is flashed into the new PCM and the vehicle will learn the new password upon the initial ignition-on cycle. If the BCM is replaced, the PCM needs to learn the new password from the BCM. The password learn procedure is as follows:

1. Attempt to the start vehicle. The vehicle will start and then stall.
2. Leave the ignition on until the Theft telltale turns off in approximately 10 minutes.
3. Turn the ignition off.
4. Restart the vehicle. The vehicle will start and on this attempt. The password is now learned.

Attempting to start the vehicle by bypassing the Passlock ll system or substituting parts without performing the password learn procedure may set a DTC P1631 and P1632.

If no password is received a DTC P1626, P1632 and U1064 may be set.

Refer to the applicable DTC for diagnoses.