The Vehicle Theft Deterrent (VTD) System, called a Passlock II System, is designed to prevent vehicle theft by disabling the engine unless the Passlock lock cylinder is correctly engaged by a mechanical key. The Passlock II System utilizes four components for theft detection: the lock cylinder, the 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 2 serial data circuit. If the password is not recognized or not present, the PCM will disable the engine. If an incorrect or no Password received, this indicates that the engine will start and stall immediately. THEFT SYSTEM telltale will flash on the IPC for approximately 4 seconds. If an incorrect or Disable Password Received , (More than three invalid passwords are received) this indicates that the engine is disabled for at least 10 minutes and that the THEFT SYSTEM telltale will flash on the IPC for approximately 4 seconds then illuminate solid on the Instrument Panel Cluster (IPC) for the 10 minutes.

After the vehicle has passed theft detection, the PCM will continue a normal engine operation. If the PCM loses the BFC communication within the same ignition cycle, the vehicle will continue to run on the following ignition cycles. This mode is called the fail enable mode. Additional information can be found in the Theft Deterrent section.

The PCM is ready to learn a new Passlock II password after the following items have been completed:

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

If no password is received, a DTC P1610 and P1632 may be set.

An intermittent may be caused by the following conditions:

Thoroughly check any suspected circuitry for the following items:

The number(s) below refer(s) to the step number(s) on the Diagnostic Table.

1. The Powertrain OBD System Check prompts you to complete some of the basic checks and to store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data captured when the fault occurred. The scan tool stores this data 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 clear.

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 Function controller (BFC) must relearn the new password. The PCM may not have finished learning the new password. Refer to the Powertrain Control Module (PCM) portion of the service manual for the password learn procedure.

4. A reprogrammed PCM does not require the password learn procedure to be performed. The password will be learned on the first ignition cycle. Refer to the latest Techline information for programming procedures. Replacement PCMs must be programmed. Reprogram the replacement PCM and perform the crankshaft position system variation learning procedure. Refer to the latest Techline procedures for PCM reprogramming and Powertrain Control Module (PCM) portion of the service manual for the crankshaft position variation learning procedure.

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