DTC B2955 (with BTM)
Diagnostic Instructions
DTC Descriptor
DTC B2955
Security Sensor Data Circuit
For symptom byte information, refer to Symptom Byte List.
Diagnostic Fault Information
Circuit/System Description
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
Conditions for Clearing the DTC
Reference Information
Schematic Reference
Immobilizer Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Testing
1. Verify DTC B2955 did not set immediately after the replacement or programming of the K9 Body Control Module or after performing the Immobilizer System Component Programming procedure.
Perform the Immobilizer System Component Programming (without BTM)Immobilizer System Component Programming (with BTM) procedure using a new vehicle key. After the new key has been learned, the existing vehicle keys may be learned to the vehicle.
2. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the K89 Immobilizer Control Module. It may take up to 2 min for all vehicle systems to power down.
3. Verify a test lamp illuminates between the low reference circuit terminal 1 and B+.
4. Ignition ON.
NOTE: In some instances, the K9 Body Control Module may only apply voltage for 3 s immediately after the ignition is turned ON. It may be necessary to monitor the DMM while turning the ignition ON to observe the voltage.
5. Test for greater than 9 V between the ignition circuit terminal 3 and ground.
6. Ignition ON.
7. Test for 10 - 13 V between the serial data circuit terminal 2 and ground.
8. Replace the K89 Immobilizer Control Module.
9. Verify DTC B2955 does not set while operating the vehicle under the conditions for running the DTC.
Replace the K9 Body Control Module.
10. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
Control Module References for body control module or immobilizer control module replacement, programming, and setup.
DTC B2955 (without BTM)
Diagnostic Instructions
DTC Descriptor
DTC B2955
Security Sensor Data Circuit
For symptom byte information, refer to Symptom Byte List.
Diagnostic Fault Information
Circuit/System Description
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 coil surrounding the ignition lock cylinder.
The transponder transmits a signal to the immobilizer control module. The immobilizer control module translates this signal to a serial data message which is sent 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
Conditions for Clearing the DTC
Diagnostic Aids
Because of how the key information is stored in the BCM and the ECM, it may be necessary to begin immobilizer programming with a new vehicle key if DTC B2955 sets immediately after attempting to program a new BCM. This will allow the key information to be transferred between the BCM and the ECM. DTC P0633 may also be set in the ECM and a "No Communication with driver ID Device" error may be displayed during the BCM programming. After programming has begun with the new vehicle key, the existing vehicle keys may then be programmed.
Reference Information
Schematic Reference
Immobilizer Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Testing
1. Verify DTC B2955 did not set immediately after the replacement or programming of the K9 Body Control Module or after performing the Immobilizer System Component Programming procedure.
Perform the Immobilizer System Component Programming (without BTM)Immobilizer System Component Programming (with BTM) procedure using a new vehicle key. After the new key has been learned, the existing vehicle keys may be learned to the vehicle.
2. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the K89 Immobilizer Control Module. It may take up to 2 min for all vehicle systems to power down.
3. Verify a test lamp illuminates between the low reference circuit terminal 1 and B+.
4. Ignition ON.
NOTE: In some instances, the K9 Body Control Module may only apply voltage for 3 s immediately after the ignition is turned ON. It may be necessary to monitor the DMM while turning the ignition ON to observe the voltage.
5. Test for greater than 9 V between the B+ circuit terminal 3 and ground.
6. Test for greater than 4 V between the serial data circuit terminal 2 and ground.
7. Ignition OFF, disconnect the X3 harness connector at the K9 Body Control Module, ignition ON.
8. Test for less than 1 V between the K89 Immobilizer Control Module serial data circuit terminal 2 and ground.
Repair the short to voltage on the circuit.
9. Replace the K89 Immobilizer Control Module.
10. Verify DTC B2955 does not set while operating the vehicle under the conditions for running the DTC.
Replace the K9 Body Control Module.
11. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
Control Module References for body control module or immobilizer control module replacement, programming, and setup.
DTC B302A
Diagnostic Instructions
DTC Descriptor
DTC B302A
Mobile Telephone Communications Interface Requested Immobilization
For symptom byte information, refer to Symptom Byte List.
Circuit/System Description
As part of the vehicle telematics enhanced services, a request may be sent to the body control module (BCM) to disable vehicle starting. If a valid message is received by the BCM requesting that starting be disabled, the start enable message will not be sent to the engine control module (ECM).
Conditions for Running the DTC
The BCM continuously monitors for this DTC.
Conditions for Setting the DTC
A start disable message has been received from the telematics module.
Action Taken When the DTC Sets
Vehicle starting will be suspended and the security indicator will be illuminated.
Conditions for Clearing the DTC
Diagnostic Aids
Reference Information
Schematic Reference
Immobilizer Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Verification
1. Verify the OnStar system is not damaged and is operating properly, with no DTCs set.
These concerns must be corrected before the start disable can be removed.
2. Press the blue OnStar button and ask the advisor to be transferred to the stolen vehicle team to verify the vehicle account has been updated.
3. Verify that OnStar is aware the vehicle has been recovered and that the vehicle account has been updated.
Contact the customer and advise them that for security purposes, they must contact OnStar and the law enforcement agency to update the vehicle account.
4. Once the vehicle account has been updated and the start disable request has been removed, DTC B302A will transition to a history DTC. Clear the history DTC.
DTC B3031
Diagnostic Instructions
DTC Descriptor
DTC B3031
Security Controller In Learn Mode
For symptom byte information, refer to Symptom Byte List.
Circuit/System Description
When learning a coded key, the body control module (BCM) is placed in learn mode. DTC B3031 will set automatically as an indicator that the system is in learn mode and not as a fault indicator. On some model year vehicles the instructions for adding keys includes the direction to always use two learned keys. This DTC will set if that direction is not followed. If only one learned key is available then Replacing Keys must be performed. Once the coded key is learned, learn mode will be exited and the DTC cleared. If the BCM does not exit learn mode, DTC B3031 will remain current and indicate a fault.
The instrument cluster security indicator will illuminate and the driver information center will display a message.
Conditions for Running the DTC
The immobilizer system is the learn coded keys state.
Conditions for Setting the DTC
The DTC will set any time the BCM enters the learn coded keys state.
Action Taken When the DTC Sets
The security indicator will illuminate. The driver information center will display a message.
Conditions for Clearing the DTC
Reference Information
Schematic Reference
Immobilizer Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Verification
1. Verify all available keys are correct for the vehicle. This can be accomplished by comparing the part number that is laser etched on the key to the part number listed in the parts catalog.
NOTE: On some model year vehicles two learned keys are required to add additional keys. If only one learned key is used, this DTC will set. If only one learned key is available then Replacing Keys must be performed.
Replace the key
2. Verify the scan tool Immobilizer data displays two or more keys learned to the vehicle.
Add one additional key
3. Perform the Replacing Keys procedure. Refer to Key with Integrated Transmitter Programming (without BTM) Key with Integrated Transmitter Programming (with BTM).
4. Verify the K9 Body Control Module learns the vehicle key and exits the learn coded key state. The scan tool Master Keys Learned parameter should increment to 1.
Replace the K9 Body Control Module
5. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
Control Module References for body control module replacement, programming, and setup.
DTC B3055
Diagnostic Instructions
DTC Descriptor
DTC B3055
No Transponder Modulation or No Transponder
For symptom byte information, refer to Symptom Byte List.
Circuit/System Description
Without BTM and/or ATH/ATS
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 coil surrounding the ignition lock cylinder.
The transponder transmits a signal to the immobilizer control module. The immobilizer control module translates this signal to a serial data message which is sent 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 and/or ATH/ATS
When a ignition key is inserted into the key pocket/slot and the ignition mode switch is pressed, the transponder embedded in the key is energized by the immobilizer antenna exciter coil. The transponder transmits a signal to the immobilizer control module. The immobilizer control module translates this signal to a serial data message which is sent 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 is unable to measure the ignition key transponder value.
Action Taken When the DTC Sets
Conditions for Clearing the DTC
Diagnostic Aids
Reference Information
Schematic Reference
Immobilizer Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Without BTM and/or ATH/ATS
1. Ignition ON.
2. Verify that DTC B1370, B1380, or B1441 is not set.
Refer to Diagnostic Trouble Code (DTC) List - Vehicle.
3. Verify the scan tool body control module Accessory parameter changes between Active and Inactive when turning the ignition ON and OFF.
Refer to Vehicle Will Not Change Power Mode.
4. Verify all available keys are correct for the vehicle. This can be accomplished by comparing the part number that is laser etched on the key to the part number listed in the parts catalog.
Replace the appropriate key.
5. Verify that DTC B3055 does not set while attempting to start the vehicle which each available key.
Replace the appropriate key.
Replace the K89 Immobilizer Control Module.
6. All OK.
With BTM and/or ATH/ATS
1. Ignition ON.
2. Verify that DTC B1370, B1380, or B1441 is not set.
Refer to Diagnostic Trouble Code (DTC) List - Vehicle.
3. Verify the scan tool body control module Accessory parameter changes between Active and Inactive when turning the ignition ON and OFF.
Refer to Power Mode Mismatch.
4. Verify all available keys are correct for the vehicle. This can be accomplished by comparing the part number that is laser etched on the key to the part number listed in the parts catalog.
Replace the appropriate key.
5. Remove the battery from each of the available vehicle keys.
6. Verify that DTC B3055 does not set while attempting to start the vehicle which each available key. To start the vehicle with the key battery removed, the key must be placed in the key pocket/slot.
Replace the appropriate key.
Replace the K89 Immobilizer Control Module.
7. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
Control Module References for immobilizer control module replacement, programming, and setup.
DTC B305C
Diagnostic Instructions
DTC Descriptor
DTC B305C
Immobilizer Transponder of Wrong Type Programmed
For symptom byte information, refer to Symptom Byte List.
Circuit/System Description
Without BTM and/or ATH/ATS
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 coil surrounding the ignition lock cylinder.
The transponder transmits a signal to the immobilizer control module. The immobilizer control module translates this signal to a serial data message which is sent 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 and/or ATH/ATS
When a ignition key is inserted into the key pocket/slot and the ignition mode switch is pressed, the transponder embedded in the key is energized by the immobilizer antenna exciter coil. The transponder transmits a signal to the immobilizer control module. The immobilizer control module translates this signal to a serial data message which is sent 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
Conditions for Setting the DTC
Action Taken When the DTC Sets
No action is taken.
Conditions for Clearing the DTC
Reference Information
Schematic Reference
Immobilizer Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON.
2. Verify all available keys/transmitters are correct for the vehicle. This can be accomplished by comparing the part number that is laser etched on the key to the part number listed in the parts catalog.
Replace the appropriate key.
3. Verify the scan tool Key Part Number parameter displays a Key Part Number when turning the ignition ON with each key.
Replace the appropriate key.
4. All OK.
DTC B3060
Diagnostic Instructions
DTC Descriptor
DTC B3060
Unprogrammed Transponder Identification Code Received
For symptom byte information, refer to Symptom Byte List.
Circuit/System Description
Without BTM and/or ATH/ATS
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 coil 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 and/or ATH/ATS
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 transponder value measured by the BCM is incorrect or not learned to the vehicle.
Action Taken When the DTC Sets
Conditions for Clearing the DTC
Reference Information
Schematic Reference
Immobilizer Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Verification
1. Perform the Replacing Keys procedure. Refer to Key with Integrated Transmitter Programming (without BTM)Key with Integrated Transmitter Programming (with BTM).
2. Verify the K9 Body Control Module learns the vehicle key. The scan tool Master Keys Learned parameter should increment to indicate another key has been learned.
Replace the key.
3. All OK.
DTC B389A
Diagnostic Instructions
DTC Descriptor
DTC B389A
Environment Identification
For symptom byte information, refer to Symptom Byte List.
Circuit/System Description
When certain modules are programmed and configured during installation, the module learns a specific environment identifier which is unique to the vehicle. The environment identifier is used to prevent the swapping modules between vehicles. The body control module (BCM) is the keeper of the environment identifier. The Instrument Cluster, Electronic Brake Control Module, HVAC Control Module, Inflatable Restraint Sensing and Diagnostic Module, engine control module (ECM), and Steering Column Lock Module (if equipped) each learn the environment identifier during their configuration process. During vehicle operation, the BCM sends the immobilizer identifier as a challenge and each module responds to the challenge by sending the environment identifier back to the BCM. If the BCM sends an incorrect immobilizer identifier or a specific number of incorrect environment identifiers are received, vehicle starting is disabled.
Conditions for Running the DTC
Ignition is in the ACCESSORY or RUN position.
Conditions for Setting the DTC
An incorrect immobilizer identifier was broadcast by the BCM.
Action Taken When the DTC Sets
Conditions for Clearing the DTC
A current DTC will be cleared when the BCM broadcasts a correct immobilizer identifier.
Diagnostic Aids
If BCM programming is not completed after BCM replacement, the immobilizer identifier will not be learned. If DTC B389A sets immediately after the replacement and programming of a BCM, perform the programming procedure again.
Reference Information
Schematic Reference
Immobilizer Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Verification
1. Verify DTC B389A did not set immediately following the replacement and programming of the K9 Body Control Module.
The immobilizer learn procedure was not properly completed. Perform the BCM immobilizer learn using the body control module IMMO Function with Existing Transponder or Remote Key in SPS. Refer to Immobilizer System Component Programming (without BTM)Immobilizer System Component Programming (with BTM).
2. Verify DTC B3902 is not set in any of the control modules listed below:
Refer to DTC B3902.
3. Perform the K9 Body Control Module immobilizer learn using body control module IMMO Function with Existing Transponder or Remote Key in SPS. Refer to Immobilizer System Component Programming (without BTM)Immobilizer System Component Programming (with BTM).
4. Verify DTC B389A does not set after programming.
Replace the K9 Body Control Module.
5. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
Control Module References for body control module replacement, programming, and setup.
DTC B3902
Diagnostic Instructions
DTC Descriptor
DTC B3902
Incorrect Immobilizer Identifier Received
For symptom byte information, refer to Symptom Byte List.
Circuit/System Description
When certain modules are programmed and configured during installation, the module learns a specific environment identifier which is unique to the vehicle. The environment identifier is used to prevent the swapping modules between vehicles. The body control module (BCM) is the keeper of the environment identifier. The instrument cluster, electronic brake control module, HVAC control module, inflatable restraint sensing and diagnostic module, engine control module (ECM), and steering column lock module (if equipped) each learn the environment identifier during their configuration process. During vehicle operation, the BCM sends the immobilizer identifier as a challenge and each module responds to the challenge by sending the environment identifier back to the BCM. If the BCM sends an incorrect immobilizer identifier or a specific number of incorrect environment identifiers are received, vehicle starting is disabled.
Conditions for Running the DTC
Ignition is in the ACCESSORY or RUN position.
Conditions for Setting the DTC
The control module's environment identifier does not match the environment identifier stored by the BCM.
Action Taken When the DTC Sets
Conditions for Clearing the DTC
A current DTC will be cleared when the module learns a correct environment identifier.
Reference Information
Schematic Reference
Immobilizer Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Verification
1. Perform the Programming and Setup procedure for the control module that set DTC B3902.
NOTE: When performing the following step, Immobilizer System Component Programming, the module may also need to be reset by using the SPS function Prepare For Removal.
2. Perform the Immobilizer System Component Programming Immobilizer System Component Programming (without BTM)Immobilizer System Component Programming (with BTM).
3. Verify DTC B3902 does not set after programming.
Replace the control module that set the DTC.
4. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
Control Module References for instrument cluster, electronic brake control module, HVAC control module, inflatable restraint sensing and diagnostic module, engine control module, or steering column lock module replacement, programming, and setup.
DTC B3924-B3928
Diagnostic Instructions
DTC Descriptor
DTC B3924
Incorrect Environmental Identifier Received From Inflatable Restraint Sensing and Diagnostic Module
DTC B3925
Incorrect Environmental Identifier Received From HVAC Control Module
DTC B3926
Incorrect Environmental Identifier Received From Instrument Cluster
DTC B3927
Incorrect Environmental Identifier Received From Electronic Brake Control Module
DTC B3928
Incorrect Environmental Identifier Received From Telematics Communication Interface Control Module
For symptom byte information, refer to Symptom Byte List.
Circuit/System Description
When certain modules are programmed and configured during installation, the module learns a specific environment identifier which is unique to the vehicle. The environment identifier is used to prevent the swapping of control modules between vehicles. The body control module (BCM) is the keeper of the environment identifier. The instrument cluster, electronic brake control module, HVAC control module, inflatable restraint sensing and diagnostic module, and telematics communication interface control module each learn the environment identifier during their configuration process. During vehicle operation, the BCM sends the immobilizer identifier as a challenge and each module responds to the challenge by sending the environment identifier back to the BCM. If the BCM sends an incorrect immobilizer identifier or a specific number of incorrect environment identifiers are received, vehicle starting is disabled.
Conditions for Running the DTC
Ignition is in the ACCESSORY or RUN position.
Conditions for Setting the DTC
The control module's environment identifier does not match the environment identifier stored by the BCM.
Action Taken When the DTC Sets
Conditions for Clearing the DTC
A current DTC will be cleared when the module learns a correct environment identifier.
Schematic Reference
Immobilizer Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Verification
1. Perform the Programming and Setup procedure for the control module that set the DTC.
2. Verify the DTC does not set after programming.
Replace the control module that set the DTC.
3. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
Control Module References for instrument cluster, electronic brake control module, HVAC control module, inflatable restraint sensing and diagnostic module, or telematics communication interface control module replacement, programming, and setup.
DTC B3935
Diagnostic Instructions
DTC Descriptor
DTC B3935
Transponder Authentication
For symptom byte information, refer to Symptom Byte List.
Circuit/System Description
Without BTM and/or ATH/ATS
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 coil surrounding the ignition lock cylinder.
The transponder transmits a signal to the immobilizer control module. The immobilizer control module translates this signal to a serial data message which is sent 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 and/or ATH/ATS
When a ignition key is inserted into the key pocket/slot and the ignition mode switch is pressed, the transponder embedded in the key is energized by the immobilizer antenna exciter coil. The transponder transmits a signal to the immobilizer control module. The immobilizer control module translates this signal to a serial data message which is sent 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
Conditions for Setting the DTC
The transponder calculation of the challenge from the BCM does not match the BCM calculation.
Action Taken When the DTC Sets
Conditions for Clearing the DTC
Reference Information
Schematic Reference
Immobilizer Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Verification
1. Ignition ON.
2. Verify the scan tool Immobilizer Allows Engine to Start parameter is Valid when using each vehicle key.
NOTE: Perform the appropriate key procedures for this vehicle. Not all vehicle models and years are the same.
Replace the keys.
3. Verify DTC B3935 does not set while operating the vehicle under the conditions for running the DTC.
Replace the K9 Body Control Module.
4. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
Control Module References for body control module replacement, programming, and setup.
DTC B3976
Diagnostic Instructions
DTC Descriptor
DTC B3976
Unconfigured Transponder
For symptom byte information, refer to Symptom Byte List.
Circuit/System Description
Without BTM and/or ATH/ATS
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 coil surrounding the ignition lock cylinder.
The transponder transmits a signal to the immobilizer control module. The immobilizer control module translates this signal to a serial data message which is sent 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 and/or ATH/ATS
When a ignition key is inserted into the key pocket/slot and the ignition mode switch is pressed, the transponder embedded in the key is energized by the immobilizer antenna exciter coil. The transponder transmits a signal to the immobilizer control module. The immobilizer control module translates this signal to a serial data message which is sent 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
Conditions for Setting the DTC
The BCM has determined the current key is not configured as a proper vehicle key.
Action Taken When the DTC Sets
Conditions for Clearing the DTC
Reference Information
Schematic Reference
Immobilizer Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Verification
1. Verify the engine starts with each available key.
Replace the key.
2. All OK.
DTC B3978-B3982
Diagnostic Instructions
DTC Descriptor
DTC B3978
Incorrect Environmental Identifier Received From Inflatable Restraint Sensing and Diagnostic Module
DTC B3979
Incorrect Environmental Identifier Received From HVAC Control Module
DTC B3980
Incorrect Environmental Identifier Received From Instrument Cluster
DTC B3981
Incorrect Environmental Identifier Received From Electronic Brake Control Module
DTC B3982
Incorrect Environmental Identifier Received From Telematics Communication Interface Control Module
For symptom byte information, refer to Symptom Byte List.
Circuit/System Description
When certain modules are programmed and configured during installation, the module learns a specific environment identifier which is unique to the vehicle. The environment identifier is used to prevent the swapping of control modules between vehicles. The body control module (BCM) is the keeper of the environment identifier. The instrument cluster, electronic brake control module, HVAC control module, inflatable restraint sensing and diagnostic Module, and telematics communication interface control module each learn the environment identifier during their configuration process. During vehicle operation, the BCM sends the immobilizer identifier as a challenge and each module responds to the challenge by sending the environment identifier back to the BCM. If the BCM sends an incorrect immobilizer identifier or a specific number of incorrect environment identifiers are received, vehicle starting is disabled.
Conditions for Running the DTC
Ignition is in the ACCESSORY or RUN position.
Conditions for Setting the DTC
An incorrect environment identifier was received by the BCM.
Action Taken When the DTC Sets
Conditions for Clearing the DTC
A current DTC will be cleared when the module learns a correct environment identifier and it is received by the BCM.
Reference Information
Schematic Reference
Immobilizer Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
1. Perform the Programming and Setup procedure for the control module that set the DTC.
2. Verify the DTC does not set after programming.
Replace the control module that set the DTC.
3. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
Control Module References for instrument cluster, electronic brake control module, HVAC control module, inflatable restraint sensing and diagnostic Module, or telematics communication interface control module replacement, programming, and setup.
DTC B3984
Diagnostic Instructions
DTC Descriptor
DTC B3984
Device 1 Environment Identifier Not Programmable
For symptom byte information, refer to Symptom Byte List.
Circuit/System Description
When certain modules are programmed and configured during installation, the module learns a specific environment identifier which is unique to the vehicle. The environment identifier is used to prevent the swapping modules between vehicles. The body control module (BCM) is the keeper of the environment identifier. The instrument cluster, electronic brake control module, HVAC control module, inflatable restraint sensing and diagnostic module, engine control module (ECM), and steering column lock module (if equipped) each learn the environment identifier during their configuration process. During vehicle operation, the BCM sends the immobilizer identifier as a challenge and each module responds to the challenge by sending the environment identifier back to the BCM. If the BCM sends an incorrect immobilizer identifier or a specific number of incorrect environment identifiers are received, vehicle starting is disabled.
Conditions for Running the DTC
Ignition is in the ACCESSORY or RUN position.
Conditions for Setting the DTC
An incorrect environment identifier is programmed or no environment identifier is programmed.
Action Taken When the DTC Sets
Conditions for Clearing the DTC
A current DTC will be cleared when the module learns a correct environment identifier.
Reference Information
Schematic Reference
Immobilizer Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Verification
1. Perform the Programming and Setup procedure for the control module that set DTC B3984.
2. Verify DTC B3984 does not set after programming.
Replace the control module that set the DTC.
3. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
Control Module References for instrument cluster, electronic brake control module, HVAC control module, inflatable restraint sensing and diagnostic module, engine control module, and steering column lock module replacement, programming, and setup.
DTC P0513
Diagnostic Instructions
DTC Descriptor
DTC P0513
Immobilizer Key Incorrect
Circuit/System Description
The body control module (BCM) sends the pre - release information to the engine control module (ECM) via the serial data circuit. The ECM then sends a challenge to the BCM. Both the ECM and BCM perform a calculation on this challenge. If the calculated response from the BCM equals the calculation performed by the ECM, the ECM will allow vehicle starting.
Conditions for Running the DTC
Ignition is in the ACCESSORY or RUN position.
Conditions for Setting the DTC
The calculated response from the BCM does not equal the calculation performed by the ECM.
Action Taken When the DTC Sets
Conditions for Clearing the DTC
Diagnostic Aids
DTC P0513 may be caused by a loose connection or intermittent poor continuity on the ECM ground or at the negative battery cable. Be sure to check the ECM ground(s) and negative battery cable if normal system diagnosis does not correct the concern.
Reference Information
Schematic Reference
Immobilizer Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Verification
1. Verify there are no immobilizer DTCs set in the K9 Body Control Module.
Refer to Diagnostic Trouble Code (DTC) List - Vehicle.
2. Perform the K9 Body Control Module immobilizer learn using the body control module IMMO Function with Existing Transponder or Remote Key in SPS. Refer to Immobilizer System Component Programming (without BTM)Immobilizer System Component Programming (with BTM).
3. Verify the engine starts after the K9 Body Control Module completes the learn procedure.
Perform the K20 Engine Control Module immobilizer learn using the engine control module IMMO Learn in SPS. Refer to Immobilizer System Component Programming (without BTM)Immobilizer System Component Programming (with BTM).
4. All OK.
DTC P0633
Diagnostic Instructions
DTC Descriptor
DTC P0633
Immobilizer Key Not Programmed
Circuit/System Description
When learning the immobilizer data, as well as the challenge and response sequence, the engine control module (ECM) is placed in learn mode. DTC P0633 will set automatically as an indicator that the system is in learn mode and not as a fault indicator. Once the immobilizer data and challenge/response are learned, learn mode will be exited when the engine is successfully started. If the ECM does not exit learn mode, DTC P0633 will remain current and indicate a fault.
Conditions for Running the DTC
The ECM is in learn mode.
Conditions for Setting the DTC
DTC P0633 will set any time the ECM enters learn mode.
Action Taken When the DTC Sets
The security indicator in the instrument cluster will illuminate.
Conditions for Clearing the DTC
Reference Information
Schematic Reference
Immobilizer Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Verification
NOTE: DTC P0633 will clear upon a successful engine start. Any malfunction that will cause a no-start condition will prevent DTC P0633 from clearing.
Prior to diagnosing DTC P0633, ensure that all power moding and engine control systems are operating properly and all conditions that may cause a no-start have been corrected. Do not replace the K20 Engine Control Module. Replacing the K20 Engine Control Module will not correct the no-start condition.
1. Verify there are no immobilizer DTCs set in the K9 Body Control Module.
Refer to Diagnostic Trouble Code (DTC) List - Vehicle.
2. Perform the K20 Engine Control Module immobilizer learn using the engine control module IMMO Learn in SPS. Refer to Immobilizer System Component Programming (without BTM) Immobilizer System Component Programming (with BTM).
3. Verify the engine starts after the K20 Engine Control Module completes the learn procedure.
An undiagnosed no-start condition exists. Refer to the appropriate subsection and diagnostic to correct the no-start condition.
4. All OK.
DTC P162B
Diagnostic Instructions
DTC Descriptor
DTC P162B
Remote Vehicle Speed Limiting Signal Message Counter Incorrect
Circuit/System Description
When a remote slow-down request is sent from OnStar, the vehicle communication interface control module sends a serial data message to the engine control module (ECM) indicating that reduced vehicle speed has been requested. Once the request is active, the ECM begins reducing engine torque to match the requested vehicle speed and the REDUCED ENGINE POWER message is displayed.
Conditions for Running the DTC
Conditions for Setting the DTC
Action Taken When the DTC Sets
Conditions for Clearing the DTC
Reference Information
Schematic Reference
OnStar/Telematics Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Remote Vehicle Speed Limiting Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Verification
1. Verify the vehicle is equipped with OnStar (RPO UE1) and DTC P162B is set
Replace the ECM.
2. Perform the Remote Vehicle Speed Limiting Reset procedure with the scan tool.
3. Verify DTC P162B is not set.
4. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
Control Module References for telematics communication interface control module or engine control module replacement, programming, and setup.
DTC P1631
Diagnostic Instructions
DTC Descriptor
DTC P1631
Immobilizer Fuel Enable Signal Not Correct
Circuit/System Description
The body control module (BCM) sends the pre - release information to the engine control module (ECM) via the serial data circuit. The ECM then sends a challenge to the BCM. Both the ECM and BCM perform a calculation on this challenge. If the calculated response from the BCM equals the calculation performed by the ECM, the ECM will allow vehicle starting. The BCM follows this action by sending the remaining immobilizer data to the ECM. If the immobilizer data sent by the BCM matches that stored by the ECM, the ECM will allow the engine to remain running.
Conditions for Running the DTC
Ignition is in the ACCESSORY or RUN position.
Conditions for Setting the DTC
The ECM receives incorrect immobilizer data from the BCM.
Action Taken When the DTC Sets
Conditions for Clearing the DTC
Reference Information
Schematic Reference
Immobilizer Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Verification
1. Verify there are no immobilizer DTCs set in the K9 Body Control Module.
Refer to Diagnostic Trouble Code (DTC) List - Vehicle.
2. Perform the K9 Body Control Module immobilizer learn using the body control module IMMO Function with Existing Transponder or Remote Key in SPS. Refer to Immobilizer System Component Programming (without BTM)Immobilizer System Component Programming (with BTM).
3. Verify the engine starts after the K9 Body Control Module completes the learn procedure.
Perform the K20 Engine Control Module immobilizer learn using the engine control module IMMO Learn in SPS. Refer to Immobilizer System Component Programming (without BTM)Immobilizer System Component Programming (with BTM).
4. All OK.
DTC P1649
Diagnostic Instructions
DTC Descriptor
DTC P1649
Immobilizer Security Code Not Programmed
Circuit/System Description
When learning the security code, as well as the challenge and response sequence, the engine control module (ECM) is placed in learn mode. Once the security code and challenge/response are learned, learn mode will be exited when the engine is successfully started.
Conditions for Running the DTC
The ECM is in learn mode.
Conditions for Setting the DTC
The ECM has not learned a security code.
Action Taken When the DTC Sets
The security indicator in the instrument cluster will illuminate.
Conditions for Clearing the DTC
Reference Information
Schematic Reference
Immobilizer Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References
Circuit/System Verification
1. Verify there are no immobilizer DTCs set in the K9 Body Control Module.
Refer to Diagnostic Trouble Code (DTC) List - Vehicle.
2. Perform the K20 Engine Control Module immobilizer learn using the engine control module IMMO Learn in SPS. Refer to Immobilizer System Component Programming (without BTM)Immobilizer System Component Programming (with BTM).
3. Verify the engine starts after the K20 Engine Control Module completes the learn procedure.
Replace the K20 Engine Control Module.
4. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
Control Module References for engine control module replacement, programming, and setup.
Symptoms - Immobilizer
IMPORTANT: The following steps must be completed before using the symptom tables.
1. Perform the Diagnostic System Check - Vehicle before using the symptom tables in order to verify that all of the following are true:
2. Review the system operation in order to familiarize yourself with the system functions. Refer to Immobilizer Description and Operation.
Visual/Physical Inspection
Intermittent
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections.
Symptom List
Refer to OnStar Stolen Vehicle Slowdown Active to diagnose the symptom.
ONSTAR STOLEN VEHICLE SLOWDOWN ACTIVE
Diagnostic Instructions
NOTE: This procedure is not used in Brazil.
Circuit/System Description
When a remote slow-down request is sent from OnStar, the Telematics Communication Interface Control Module sends a serial data message to the engine control module (ECM) indicating that reduced vehicle speed has been requested. Once the request is active, the ECM begins reducing engine torque to match requested vehicle speed and the REDUCED ENGINE POWER message is displayed.
Reference Information
Schematic Reference
OnStar/Telematics Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Master Electrical Component List
Description and Operation
Remote Vehicle Speed Limiting Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Verification
1. Verify the vehicle is not in the OnStar initiated Stolen Vehicle Slow down mode. This can be accomplished by verifying the scan tool Telematics Enhanced Service Immobilization parameter is No.
2. All OK.