B2955
DTC B2955
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC B2955 00
- Security Sensor Data Circuit Malfunction
Diagnostic Fault Information
Circuit/System Description
Without BTM/ATH
When an ignition key is inserted into the ignition lock cylinder and the ignition is switched ON, the transponder embedded in the key is energized by the exciter coils surrounding the ignition lock cylinder. The transponder transmits a signal to the body control module (BCM). The BCM then compares this value to a value stored in memory. If the value is correct, the BCM will send the prerelease password via the serial data circuit to the engine control module (ECM). If the learned key code does not match or a transponder value is not received, the BCM will send the start disable password to the ECM.
With BTM/ATH
When a keyless entry transmitter is inserted into the transmitter pocket/slot and the ignition mode switch is pressed, the transponder embedded in the transmitter is energized by the immobilizer antenna exciter coil. The transponder transmits a signal to the body control module (BCM). The BCM then compares this value to a value stored in memory. If the value is correct, the BCM will send the prerelease password via the serial data circuit to the engine control module (ECM). If the learned key code does not match or a transponder value is not received, the BCM will send the start disable password to the ECM.
Conditions for Running the DTC
Ignition is in the Accessory or Run position.
Conditions for Setting the DTC
The BCM detects a circuit fault on the immobilizer antenna circuits.
Action Taken When the DTC Sets
* Vehicle starting will be disabled.
* The security indicator in the instrument cluster will be illuminated. A service message will be displayed in the driver information center.
Conditions for Clearing the DTC
* A current DTC will be cleared when the condition for setting the DTC are no longer present.
* A history DTC will be cleared after 100 malfunction-free ignition cycles or when a scan tool is used to clear DTCs.
Reference Information
Schematic Reference
Immobilizer Schematics Immobilizer Schematics
Connector End View Reference
Component Connector End Views Sunshade - Left (D6I)
Description and Operation
Immobilizer Description and Operation Immobilizer
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Testing
1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the K89 immobilizer control module. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 30 ohm between the low reference circuit terminal 1 and ground.
• If 30 ohm or greater
1. Ignition OFF, disconnect the harness connector at the K9 body control module.
2. Test for less than 2 ohm in the low reference circuit end to end.
• If 2 ohm or greater, repair the open/high resistance in the circuit.
• If less than 2 ohm, replace the K9 body control module.
• If less than 30 ohm
3. Connect a test lamp between the B+ circuit terminal 3 and ground.
4. Verify the test lamp illuminates for three seconds after turning the ignition ON.
• If the test lamp does not illuminate
1. Ignition OFF, disconnect the harness connector at the K9 body control module.
2. Test for infinite resistance between the B+ circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohm in the B+ circuit end to end.
• If 2 ohm or greater, repair the open/high resistance in the circuit.
• If less than 2 ohm, replace the K9 body control module.
• If the test lamp illuminates
5. Ignition ON.
6. Test for 10-13 V between the serial data circuit terminal 2 and ground.
• If less than 10 V
1. Ignition OFF, disconnect the harness connector at the K9 body control module.
2. Test for infinite resistance between the serial data circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohm in the serial data circuit end to end.
• If 2 ohm or greater, repair the open/high resistance in the circuit.
• If less than 2 ohm, replace the K9 body control module.
• If greater than 13 V
1. Ignition OFF, disconnect the harness connector at the K9 body control module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K9 body control module.
• If between 12-13 V
7. Replace the K89 immobilizer control module.
8. Verify DTC B2955 does not set while operating the vehicle under the conditions for running the DTC.
• If DTC B2955 is set
Replace the K9 body control module.
• If DTC B2955 is not set
9. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Theft Deterrent Module Replacement Service and Repair
* Control Module References Control Module References for BCM replacement, programming, and setup