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 BCM will send a password to the PCM through the Class 2 serial data circuit. If the BCM's 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 to 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 the SYSTEM telltale will flash on the IPC for approximately 4 seconds, then will illuminate solid on the instrument panel cluster (IPC) for 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 of this document.

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 inspect any suspected circuitry for the following items:

The numbers below refer to the step numbers on the diagnostic table.

1. The Powertrain On-Board Diagnostic (OBD) System Check prompts the technician to complete some basic diagnostics and to store the Freeze Frame and Failure Records data on the scan tool, if applicable. This creates an electronic copy of the data that was 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 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 Procedure in the supporting text.

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 refer to the supporting text for the Crankshaft Position Variation Learn Procedure.

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