U1255

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Circuit Description

This circuit supplies the Passlock data to the Vehicle Control Module (VCM)/Powertrain Control Module (PCM) from the Passlock(TM) Module, as well as communicating all of the Class 2 messages among all of the modules and the tool, CKT 1807 (PPL).

Conditions for Setting the DTC

All of the following conditions must be met:

^ The ignition is active.
^ Communication with the Data Link Connector and other modules is lost or at least has been lost at one time due to intermiffent connection (this is usually a DTC).

Action Taken When the DTC Sets

^ Stores DTC U1125 in the Passlock(TM) Module memory.
^ If the ignition was OFF at the time, the vehicle will not start again.
^ If the engine was running at the time, the vehicle will start again but the SECURITY indicator will remain illuminated.

Conditions for Clearing the DTC

^ The Passlock(TM) Module continuously monitors the signal and moves the DTC from current to history on the next ignition cycle when the condition causing the fault no longer exists.
^ All Passlock(TM) Module history codes will be cleared after 100 ignition cycles (from OFF to RUN) with no current codes active during the 100 ignition cycles.
^ Using a scan tool.

Diagnostic Aids

^ When the diagnostics direct you to take electrical measurements at the Wiring Harness Junction Blocks, refer to Inline Harness Connector End Views in Wiring Systems for terminal assignments of the Wiring Harness Junction Blocks.
^ If the DTC is a history DTC, the problem may be intermittent. Try performing the test shown while wiggling wiring and connectors, this can often cause the malfunction to appear.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

1. The VTD Diagnostic System Check will test the scan tool's ability to communicate with the EVO/Passlock Module and the Vehicle Control Module VCM/Powertrain Control Module (PCM). If communications are unable to be established with either module a CURRENT fault exists. This fault could be caused by a faulty power or ground circuit to the affected module, a faulty CKT 1807 (PPL), or a faulty control module. The VTD Diagnostic System Check table will determine if power or ground circuits are faulty. If the power and grounds test OK, you are referred to A Diagnostic System Check - Data Link Communications to diagnose CKT 1507 (PPL) or a faulty EVO/Passlock Module.

2. This step is to determine if the scan tool can use CKT 1807 (PPL) to communicate with the VCM/PCM.

3. This step is to determine the problem with CKT 1807 (PPL). Whether it is fault of the circuit or fault of the Passlock(TM) Module.

4. In this step be sure to connect all connectors removed during the diagnosis and perform the reprogramming of the Passlock(TM) Module.