Service Information

Volt

DTC C012D, C120A, C128A, C128D, C12BC, or C12BE

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 C012D 00: Brake Boost Regulation Pressure Sensor Malfunction

DTC C012D 01: Brake Boost Regulation Pressure Sensor Short to Battery

DTC C012D 06: Brake Boost Regulation Pressure Sensor Low Voltage/Open

DTC C012D 0F: Brake Boost Regulation Pressure Sensor Signal Erratic

DTC C012D 11: Brake Boost Regulation Pressure Sensor High Input

DTC C012D 5A: Brake Boost Regulation Pressure Sensor Not Plausible

DTC C120A 00: ABS Pump Pressure Performance

DTC C128A 00: ABS Boost Pressure Sensor Offset Error

DTC C128D 00: ABS Boost Pressure Sensor Offset Error

DTC C12BC 00: ABS Boost Pressure Sensor Circuit Open or Short to Ground

DTC C12BE 00: ABS Boost Pressure Sensor Erratic

Circuit/System Description

The electronic brake control module uses input from the boost pressure sensor for more accurate control during brake and vehicle stability enhancement system event. The boost pressure sensor is internal to the brake pressure modulator valve assembly.

Conditions for Running the DTC

•	Vehicle ON or Vehicle in Service Mode.

•	The ignition voltage is greater than 10 V.

Conditions for Setting the DTC

C012D 00, C128D 00, C012D 11 or C128A 00

Internal sensor failure is detected.

C012D 01

A short to battery is detected on the sensor signal circuit.

C012D 06 or C12BC 00

A short to ground or open is detected signal circuit.

C012D 5A or C120A 00

The boost pressure being commanded is not being achieved.

C012D 0F or C12BE 00

Signal is erratic and changes faster than physically allowed.

Action Taken When the DTC Sets

•	The electronic brake control module disables the ABS and vehicle stability enhancement system for the duration of the drive cycle.

•	A driver information centre message and/or a warning indicator may be displayed.

Conditions for Clearing the DTC

•	The condition for setting the DTC is no longer present.

•	The electronic brake control module clears the history DTC when a current DTC is not detected in 40 consecutive drive cycles.

Reference Information

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

Vehicle in Service Mode.
Verify that no other electronic brake control module DTCs are set.

⇒	*If any DTC are set*

Refer to Diagnostic Trouble Code (DTC) List - Vehicle

⇓	*If none DTCs are set*

Perform the Electronic Brake Control Module Learn procedure with a scan tool.
Verify that DTC C012D, C120A, C128A, C128D, C12BC, or C12BE is not set.

⇒	*If any listed DTCs are set*

4.1.	Replace the Q5 Brake Pressure Modulator.

4.2.	Verify the DTC does not reset.

⇒	If the DTC resets, replace the K17 Electronic Brake Control Module.

⇓	*If none of the listed DTCs are set*

All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

•	Electronic Brake Control Module with Brake Pressure Modulator Valve Replacement

•	Control Module References for electronic brake control module replacement, programming and setup