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 ignition 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 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 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 - there is no communication between the BCM and 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 from the BCM that does not match, or more than three invalid passwords other than Fuel Disabled or Undecided are received. |
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.
Conditions for Setting the DTC
The PCM is ready to learn a new Passlock II password after the following items have been completed:
| • | The PCM received an incorrect password. |
| • | The PCM finished the 10 minute learn pending timer, ie. leaving the ignition switch ON for 10 minutes. |
Action Taken When the DTC Sets
| • | The PCM will record operating conditions at the time the diagnostic fails. This information will store in the Freeze Frame and Failure Records buffers. |
| • | A history DTC stores. |
Conditions for Clearing the MIL/DTC
| • | As soon as one correct password is received at key up this becomes a history code. A correct password is anything but a Fuel Disabled or an Undecided password |
| • | A history DTC will clear after 40 consecutive warm up cycles without a fault. |
| • | Use a scan tool can 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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This DTC is normally set and cleared during a password learn procedure. If the password learn procedure is not completed, this DTC will not be cleared.
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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 P1630 active? | -- | ||
3 | Is DTC P1632 also set? | -- | ||
4 | Is DTC U1064 also set? | -- | Go to DTC U1001-U1254 Loss of XXX Communications in Data Link Communications | |
5 | Observe for any body control module (BCM) DTCs related to the theft deterrent system with the scan tool. Were any BCM DTCs set? | -- | Go to Diagnostic System Check - Body Control System in Body Control System | |
6 | Check 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 | |
Does the engine start and continue to run? | -- | |||
8 |
Was a problem found? | -- | ||
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 |
