The powertrain control module (PCM) controls the fuel injector operation and the starter operation based on a vehicle theft deterrent (VTD) password from the theft deterrent module. When the ignition is first turned ON, the theft deterrent module sends a programmed theft deterrent password to the PCM. The PCM acknowledges the password and responds to the VTD module that normal fuel injector and starter operation will continue. If the PCM detects an incorrect password due to a theft deterrent system failure or an attempted vehicle theft, DTC 1631 will set. The engine will not crank as long as the condition is present. Refer to Diagnostic System Check - Theft Deterrent and Vehicle Theft Deterrent (VTD) Operation in Theft Deterrent.

The ignition is ON.

The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.

DTC P1631 indicates that the vehicle theft deterrent password the PCM has learned does not agree with the password being received from the theft deterrent system. This condition can occur if an incorrect key is used when attempting to start the vehicle or if the VTD module has been replaced and the PCM Password Learn function has not been enabled. If the VTD module has been replaced, the password must be relearned.