B2957

Circuit Description
The Body control module (BCM) will read an analog voltage form the Passlock sensor. Based on an internal reference, the BCM will determine if the measured voltage is in 1 of the following conditions:
- Open
- Shorted to ground
- A valid code
- A tamper code
There are 10 possible valid code combination. The BCM will only recognize the last learned valid code.

Conditions for Setting the DTC
- The ignition switch is ON.
- The BCM signal input is less than 0.4 volts for 1 second after turning the ignition switch to the CRANK position.

Action Taken When the DTC Sets
- The vehicle will not start if the fault occurs before you start the vehicle. The security telltale will flash for 10 minutes then turn ON steady.
- If the vehicle is running when the fault occurs, the BCM will be in the fail enable mode allowing the vehicle to start and run. The security telltale will be ON.

Conditions for Clearing the DTC
- The DTC will clear once the ignition cycle has occurred without the fault recurring.
- The BCM history codes will clear once 100 concurrent ignition cycles occur without the fault recurring.
- Using a scan tool.

Diagnostic Aids
- When replacing the Passlock sensor, all of the following components are included as a replacement part and must be replaced:
- The lock
- The sensor
- The filter
- The harness
- Use a scan tool in order to inspect the Passlock data voltage and the Passlock code.
- Perform a visual inspection of the wiring and the connectors.
- Inspect the Passlock sensor harness for an intermittent or a short to battery. Refer to Intermittents and Poor Connections in Overall Vehicle Information/Testing and Inspection.
- Following a repair the tamper timer needs 10 minutes in order to expire.

Steps 1 - 4:

Step 5:

Step 6:

Steps 7 - 10:

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step inspects for a short to ground in the Passlock signal circuit.
3. This step inspects for a short between the Passlock signal circuit and the Passlock sensor ground circuit.
5. This step isolates the short to ground between the Passlock sensor and the harness.
8. This step isolates short in CKT 1057 to the short in CKT 1836 between the Passlock sensor and the harness.