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. Refer to Testing for Intermittent Conditions and Poor Connections . |
| • | 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. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies that DTC B2955 is current.
-
This step tests for proper operation of the circuit in the high voltage range.
-
This step tests for any device that may prevent proper Passlock system operation.
-
This step tests for a voltage drift within the Passlock sensor.
-
This step verifies correct signal circuit voltage to Passlock sensor.
-
This step tests for proper operation of the circuit in the low voltage range.
-
This step tests for high resistance or an open in the 12-volt reference circuit.
-
This step tests for a short to ground in the Passlock signal circuit.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Immobilizer Schematics | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
Does the scan tool display DTC B2955 as a current DTC? | -- | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections | |
Does the scan tool indicate that the Passlock data voltage is within the specified range? | 0.4-4.9 V | Go to Step 4 | Go to Step 8 | |
4 | Have you replaced the Passlock sensor on this vehicle? | -- | Go to Step 5 | Go to Step 6 |
5 | Have you performed a Passlock learn procedure after replacing the Passlock sensor? | -- | Go to Step 7 | Go to Step 19 |
Inspect the area around the ignition lock cylinder for any device which could create a magnetic field, such as an audio speaker, a magnet, etc. Is there a magnet device near the ignition lock cylinder? | -- | Go to Step 17 | Go to Step 7 | |
With a scan tool, observe the Passlock data voltage for one minute. Does the scan tool indicate that the Passlock data voltage is changing more than the specified value? | +/- 0.02 V | Go to Step 16 | Go to Step 8 | |
Does the scan tool indicate that the Passlock Data Voltage is greater than the specified value? | 4.9 V | Go to Step 9 | Go to Step 12 | |
Does the scan tool indicate that the Passlock Data Voltage is less than the specified value? | 0.4 V | Go to Step 10 | Go to Step 11 | |
Does the voltage measure less than the specified value? | 12 V | Go to Step 13 | Go to Step 16 | |
11 | Test the signal circuit of the Passlock sensor for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 14 |
Test the Passlock sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 15 | |
13 | Test the 12-volt reference circuit of the Passlock sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 14 |
14 | Test the ground circuit of the Passlock sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 15 |
15 | Inspect for poor connections and the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 20 |
16 | Inspect for poor connections and the Passlock sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 18 |
17 | Remove the device creating the magnetic force. Did you find and correct the condition? | -- | Go to Step 21 | -- |
18 | Replace the Passlock sensor. Refer to Ignition Lock Cylinder Case Replacement . Did you complete the repair? | -- | Go to Step 19 | -- |
19 | Perform the Programming Theft Deterrent System Components . Is the repair complete? | -- | Go to Step 21 | -- |
20 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 21 | -- |
21 | You may have to wait up to 10 minutes in order to reset the BCM and synchronize all of the Passlock components.
Does the DTC reset? | -- | Go to Step 3 | Go to Step 22 |
22 | Attempt to start the vehicle. Does the engine start and run? | -- | System OK | Go to Step 3 |
