Buick Regal: DTC C012A

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 Descriptors

DTC C012A

Brake Master Cylinder Pressure Sensor

For symptom byte information refer to Symptom Byte List.

Circuit/System Description

The brake pressure sensor is integral to the brake pressure modulator valve assembly. The electronic brake control module monitors the brake pressure sensor supply voltage and the signal voltage. The body control module sends a serial data message when the brake pedal is applied. The electronic brake control module uses input from the master cylinder pressure sensor for more accurate control during a vehicle stability enhancement system event.

Conditions for Running the DTC

Ignition ON, the brake pedal is not applied.

Conditions for Setting the DTC

• The master cylinder pressure sensor raw offset is out of specified range.
• An internal electronic or mechanical fault is detected in the master cylinder pressure sensor.

Action Taken When the DTC Sets

• The electronic brake control module disables the ABS, traction control, stability control and hill start assist for the duration of the ignition cycle.
• The ABS warning indicator turns ON.
• The traction control/stability control-active indicator turns ON.

Conditions for Clearing the DTC

• A current DTC clears when the diagnostic runs and passes.
• The electronic brake control module will turn OFF the indicators in the next ignition cycle.

Reference Information

Schematic Reference

Antilock Brake System Wiring Schematics

Connector End View Reference

Component Connector End View Index

Description and Operation

ABS 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 Testing

1. Ignition ON.

2. Verify that DTC C012A is not set.

• If DTC C012A is set

1. Replace the Q5 Brake Pressure Modulator.
2. Verify that DTC C012A is not set while driving the vehicle under normal braking conditions.
   • If DTC C012A is set, replace the K17 Electronic Brake Control Module.
   • Go to next step: If DTC C012A is not set.
3. All OK.

• Go to next step: If DTC C012A is not set

3. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for Electronic Brake Control Module replacement, programming and setup.

DTC C0131

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 Descriptors

DTC C0131

Antilock Braking System Pressure Circuit

For symptom byte information refer to Symptom Byte List.

Circuit/System Description

The electronic brake control module monitors the brake pressure sensor which is integral to the brake pressure modulator. The body control module monitors the brake pedal position sensor signal when the brake pedal is applied and sends a serial data message to the electronic brake control module indicating the brake pedal position. The electronic brake control module compares the brake pressure to the actual brake pedal position and uses this information for vehicle stability control.

Conditions for Running the DTC

• The engine is running.
• The brake pedal has been applied and released.

Conditions for Setting the DTC

C0131 00

The electronic brake control module detects an invalid or erratic brake pressure sensor signal.

C0131 1A

The offset value of the pressure sensor is out of the specified range.

C0131 3B

The brake pressure sensor is not calibrated.

C0131 5A

• The brake pressure sensor offset is out of the specified range.
• The electronic brake control module detected an invalid or erratic brake pressure.
• The brake pressure is not plausible with the vehicle acceleration or deceleration.

Action Taken When the DTC Sets

• The traction/stability control indicator turns ON.
• The electronic brake control module disables the traction/stability for the duration of the ignition cycle.

Conditions for Clearing the DTC

• The DTC clears when the diagnostic runs and passes.
• The history DTC will clear after 40 consecutive fault-free ignition cycles have occurred.

Reference Information

Schematic Reference

Antilock Brake System Wiring Schematics

Connector End View Reference

Component Connector End View Index

Description and Operation

ABS 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. Apply and release brake pedal. Verify the brake stop lamps operate properly.

• If the brake stop lamps do not operate properly
• Refer to Symptoms - Lighting.
• Go to next step: If the brake stop lamps operate properly

3. Verify that DTC C0131 is not set.

• If the DTC is set
• Replace K17 Electronic Brake Control Module.
• Go to next step: If the DTC is not set

4. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Control Module References provides information for control module replacement, programming and setup.

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