B2955

DTC B2955

Circuit Description

The Passlock system is provided in order to prevent vehicle theft if the ignition lock is forced to rotate or the ignition switch is operated while separated from the ignition lock cylinder case. The body control module (BCM) provides security system sensor power and low reference for the Passlock sensor. The BCM also measures the security system sensor voltage. When the correct key is used to start the vehicle, a magnet on the lock cylinder passes close to the Passlock sensor within the ignition lock cylinder case. The magnet activates the security hall effect sensor in the Passlock sensor which completes a circuit from the security sensor signal circuit through a resistor to the security sensor low reference circuit. The resistance value will vary from vehicle to vehicle. The BCM will measure the voltage on the security sensor signal circuit and compare this voltage to a previously learned voltage. If the voltage measured is within the valid range, the BCM will send a class 2 message to the powertrain control module (PCM) to enable vehicle starting. If the voltage measured is not within the valid range, a class 2 message will be sent to the PCM to disable starting of the vehicle.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2955 Security System Sensor Data Circuit

Conditions for Running the DTC

* The ignition switch is ON.
* The BCM will inspect for a valid or tamper code when the ignition is rotated from ON to CRANK and will continue to monitor the signal during the engine running period.

Conditions for Setting the DTC

* The BCM signal input is greater than 4.9 volts, or less than 0.4 volts for 1 second after turning the ignition switch to the CRANK Position
* The BCM is reading a valid but different code value than previously learned, or a tamper from the Passlock sensor.

Action Taken When the DTC Sets

* The vehicle will not start if the fault occurs before you start the vehicle. The security indicator will be FLASHING.
* 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 indicator will be ON.
* The DTC will set only when the engine is running.
* The BCM will be in the fail enable mode allowing the vehicle to start and run.
* The vehicle will not run. The security indicator will be flashing.
* The Passlock state is Tamper.

Conditions for Clearing the MIL/DTC

* The DTC will clear once an ignition cycle occurs without the fault recurring.
* The BCM history coded will clear once 100 concurrent ignition cycles occur without the fault recurring.
* Using a scan tool.

Diagnostic Aids

* Use the scan tool in order to inspect the Passlock data voltage and the Passlock code.
* Inspect the Passlock sensor harness at the Passlock sensor and the lower steering column connector for an intermittent, short to ground or short to battery.
* Following a repair the tamper timer may need 10 minutes in order to expire.
* You may be directed to this table from the VTD Diagnostic System Check without a DTC B2955 being set. If you were directed to this table, follow all of the steps in this diagnostic table.
* When directed to this table DTC B2955 may have a history status.
* The VTD internal diagnostics are not run while the tamper timer is active.
* Prior to replacing a BCM, ensure that all of the diagnostics have been completed. Refer to the diagnostic trouble code (DTC) list. Diagnostic Trouble Code (DTC) List - Vehicle

Test Description

Step 1 - Step 10:

Step 11 - Step 22:

The numbers below refer to the step numbers on the diagnostic table.
2. This step verifies that DTC B2955 is current.
3. This step tests for proper operation of the circuit in the high voltage range.
6. This step tests for any device that may prevent proper Passlock system operation.
7. This step tests for a voltage drift within the Passlock sensor.
8. This step verifies correct signal circuit voltage to Passlock sensor.
9. This step tests for proper operation of the circuit in the low voltage range.
10. This step tests for high resistance or an open in the 12-volt reference circuit.
12. This step tests for a short to ground in the Passlock signal circuit.