The vehicle theft deterrent system is designed to prevent vehicle theft by disabling the engine unless the lock cylinder is correctly engaged by a mechanical key. The theft deterrent system utilizes four components for theft detection, the lock cylinder, ignition switch, the Body Function Controller (BFC) and the Powertrain Control Module (PCM).

When starting the engine, the PCM looks for a password from the Body Function Controller (BFC) through the Class II serial data circuit. If the password is not recognized or not present, the PCM will disable the engine. There are two modes of tamper detection:

After the vehicle has passed theft detection, the PCM will continue normal engine operation. Additional information can be found in Theft Deterrent Systems.

The PCM remains in theft deterrent password learn mode for greater than 2 seconds.

A new replacement PCM will be in a functional state to learn the password from the BCM. If the BCM is replaced, the PCM must be placed in password learning mode to relearn a new password. Once learned, the password becomes permanent information that remains with the vehicle. The loss of PCM battery or ignition voltage will not affect the programmed password information.

Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals and Connector Repairs in Wiring Systems.

Refer to Body Control Module (BCM) Programming/RPO Configuration for information concerning the password learning procedure.

If the Body Function Controller (BFC) is replaced the PCM must be reflashed to allow the new password to be learned. The ignition must be turned off for at least 30 seconds then on for the PCM to learn the new BFC password.

Number(s) below refer to the step number(s) on the Diagnostic Table:

1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

2. This DTC is normally set and cleared during a password learn procedure. If the password learn procedure is not completed, this DTC will not be cleared.

3. The theft deterrent password resides in the Body Function controller (BFC). Anytime a VTD component has been replaced, the Powertrain Control Module (PCM) and Body Control Module (BCM) must relearn the new password. The PCM may not have finished learning the new password.

   If the serial data loss occurred after a good theft password has been received, the PCM must be reprogrammed and the password learn and the crankshaft position variation learn procedures must be completed to allow the theft system to operate properly.

4. Replacement PCMs must be programmed. A reprogrammed PCM does not require the password learn procedure to be performed. The password will be learned on the first ignition cycle. The replacement PCM must be reprogrammed and the crankshaft position system variation procedure must be performed.

6. If no malfunctions have been found at this point and no additional DTCs were set, refer to Diagnostic Aids for additional checks and information.