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 the four following components for theft detection:

When the ignition switch is first turned ON, the body control module (BCM) will send a password to the PCM through the class 2 serial data circuit. If the BCMs password does not match the password that is stored in the PCM, the PCM will disable the engine. This will cause the engine to start and stall immediately or not start at all.

The SYSTEM telltale will flash on the IPC and the engine is disabled until a matching password is received. The password is checked every 4 seconds. The engine is disabled for at least 10 minutes and that the SYSTEM telltale will flash on the IPC for approximately 4 seconds then illuminate solid on the instrument panel cluster (IPC) for the 10 minutes for the following passwords received:

The following are four situations in which the PCM and BCM passwords would not match:

After the vehicle has passed theft detection, the PCM will continue a normal engine operation. If the PCM loses the BCM 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.

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 U1064 and P1632 may be set.

An intermittent may be caused by the following conditions:

Thoroughly check any suspected circuitry for the following items:

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 malfunction occurred. The information is then stored in the scan tool for later reference.

4. The scan tool can display whether or not the Body Control Module (BCM) has received and learned the password from the lock cylinder. If the password is not received, the reason the PCM set this DTC may due to a password that has not yet been learned due to a component being replaced, or a problem in the BCM or a VTD component.

6. A Passlock theft deterrent DTC being set indicates that a Passlock II component may be malfunctioning.

8. The PCM may not have learned the new password. Refer to the Password Learn .

9. Replacement PCMs must be reprogrammed. 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. The replacement PCM must be reprogrammed and the crankshaft position system variation procedure must be performed. Refer to the latest Techline procedures for PCM reprogramming and the Crankshaft Position System Variation Learn portion of the service manual for the Crankshaft Position Variation Procedure.

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