Circuit Description
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 uses the four following components for theft detection:
| • | The lock cylinder |
| • | The ignition switch |
| • | The body control module (BCM) |
| • | The Powertrain Control Module (PCM) |
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 instrument control panel (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 will illuminate solid on the IPC for 10 minutes for the following passwords received:
| • | Fuel disabled |
| • | Undecided |
| • | Mismatched |
The following are four situations in which the PCM and BCM passwords would not match:
| • | The PCM does not receive a password from the BCM - there is no communication between the BCM and the PCM. |
| • | The BCM sends a Fuel Disabled password, indicating that a tamper has occurred. |
| • | The BCM sends an Undecided password. |
| • | The PCM receives a password other than Fuel Disabled or Undecided, or more than three invalid passwords. |
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.
Conditions for Setting the DTC
A password other than the Fuel Disabled or Undecided password that does not match is sent to the PCM from the BCM.
Action Taken When the DTC Sets
| • | The PCM will record the operating conditions at the time during which the diagnostic fails. This information will store in the Freeze Frame and Failure Records buffers. |
| • | A history DTC stores. |
| • | The fuel system is disabled by the PCM. |
Conditions for Clearing the MIL/DTC
| • | As soon as one good, or matching, password is received at key-up this becomes a history code. A good password is anything but a Fuel Disabled or Undecided password. |
| • | A history DTC will clear after 40 consecutive warm-up cycles without a fault. |
| • | Use a scan tool to clear the DTCs. |
Diagnostic Aids
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:
| • | A faulty electrical terminal connection |
| • | A broken wire inside the insulation |
Thoroughly check any suspected circuitry for the following items:
| • | Backed-out terminals or improper mating |
| • | Improperly formed or damaged terminals |
| • | Faulty terminal-to-wire connections |
| • | Physical damage to the wiring harness |
| • | Corrosion |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The Powertrain On-Board Diagnostic (OBD) System Check prompts the technician to complete some basic diagnostic 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.
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A BCM Passlock™ theft deterrent DTC being set indicates that a Passlock II™ component may be malfunctioning. Refer to the applicable BCM table for diagnosis.
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The theft deterrent password resides in the body control module (BCM). Anytime a VTD component is replaced, the PCM must relearn the new BCM password. Refer to Password Learn Procedure in the supporting text.
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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 CKP System Variation Learn Procedure portion of the service manual.
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If no malfunctions have been found at this point and no additional DTCs were set, refer to Diagnostic Aids for additional checks and information.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | |||
2 |
Were any BCM DTCs set? | -- | Go to Diagnostic System Check - Body Control System in Body Control Systems. | |
Use the scan tool to heck the BCM for any Passlock™ Theft Deterrent DTCs. Were any Passlock™ Theft Deterrent DTCs set? | -- | Go to Diagnostic Starting Point in Theft Deterrent. | ||
Does the engine start and continue to run? | -- | |||
5 | Use the scan tool to check for any new DTCs. Was any new DTCs set? | -- | Go to the applicable DTC table | |
|
Important: Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | -- | ||
7 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | ||
Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | Go to the applicable DTC table | System OK |
