Buick Regal: DTC B305C

Diagnostic Instructions

• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provides an overview of each diagnostic category.

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

• Ignition is in the Accessory or Run position
• Battery voltage is greater than 9 volts
• Transponder authentication has occurred

Conditions for Setting the DTC

• The programed transponder type does not match the equipped system on the vehicle.
• A transponder used for vehicles without BTM and/or ATH/ATS has been programmed to a vehicle with BTM and/or ATH/ATS.
• A transponder used for vehicles with BTM and/or ATH/ATS has been programmed to a vehicle without BTM and/or ATH/ATS.

Action Taken When the DTC Sets

No action is taken.

Conditions for Clearing the DTC

• A current DTC will be cleared when the BCM detects a programed transponder type that matches the equipped system on the vehicle.
• A history DTC will be cleared after 100 malfunction-free ignition cycles.

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

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

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.

• If a key is not correct

Replace the appropriate key.

• Go to next step: If all keys are correct

3. Verify the scan tool Key Part Number parameter displays a Key Part Number when turning the ignition ON with each key.

• If a Key Part Number is not read

Replace the appropriate key.

• Go to next step: If a Key Part Number is read for each key

4. All OK.

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