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 utilizes the four following components for theft detection:
| • | The lock cylinder |
| • | The iIgnition switch |
| • | The body control module (BCM) |
| • | The powertrain control module (PCM) |
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:
| • | 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, indicating that there is no communication between the BCM and PCM. |
| • | The BCM sends a Fuel Disabled password, indicating that tampering has occurred. |
| • | The BCM sends an Undecided password to the PCM. |
| • | The PCM receives more than three invalid passwords from the BCM, other than Fuel Disabled or Undecided passwords. This ordinarily occurs when the PCM or BCM has been replaced |
After the vehicle has passed theft detection, the PCM will continue normal engine operation. If the PCM loses communication with the BCM during the same ignition cycle, the vehicle will continue to run during subsequent 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
| • | The PCM receives a fuel disabled password from the BCM. |
| • | The PCM receives an undecided password from the BCM. |
| • | The PCM receives no password from the BCM. |
| • | The PCM receives a password which did not match the PCM password 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 be stored 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 does not include Fuel Disabled or Undecided passwords. |
| • | 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 inspect 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 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.
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A passlock theft deterrent DTC being set indicates that a Passlock II component may be malfunctioning.
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The PCM may not have learned the new password.
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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.
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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 | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
2 |
Is DTC U1064 also set? | -- | Go to DTC U1001-U1254 Loss of XXX Communications in Data Link Communications | |
3 | Is DTC P1630 and P1632 set together? | -- | ||
Is DTC P1631 and P1632 set together? | -- | |||
5 | Check the body control module (BCM) for any DTCs with the scan tool. Were any BCM DTCs set? | -- | Go to Diagnostic System Check - Body Control System in Body Control Systems | |
Observe the BCM for any passlock theft deterrent DTCs with the scan tool. Were any passlock theft deterrent DTCs set? | -- | Go to Diagnostic System Check - Theft Deterrent in Theft Deterrent | ||
7 |
Was a problem found? | -- | ||
Does the engine start and continue to run? | -- | |||
Important: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Did you complete the repair? | -- | -- | ||
10 |
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 |
