Service Information

Volt

DTC C012C, C121A, C128C, C128F, C12B9, C12BA, C12BB, or C12F7

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 C12F7 00: ABS Boost Pressure Sensor and Regenerative Axle Pressure Sensor Not Plausible

DTC C128F 00: ABS Regenerative Axle Pressure Sensor Raw Offset Error

DTC C012C 01: Regenerative Axle Pressure Sensor Short to Battery

DTC C12BA 00: ABS Regenerative Axle Pressure Sensor Circuit Short To Battery

DTC C012C 06: Regenerative Axle Pressure Sensor Low Voltage/Open

DTC C12B9 00: ABS Regenerative Axle Pressure Sensor Circuit Open or Short To Ground

DTC C012C 11: Regenerative Axle Pressure Sensor High Input

DTC C128C 00: ABS Regenerative Axle Pressure Sensor Offset Error

DTC C012C 0F: Regenerative Axle Pressure Sensor Signal Erratic

DTC C12BB 00: ABS Regenerative Axle Pressure Sensor Erratic

DTC C121A 00: ABS Regenerative Axle Pressure Performance

Circuit/System Description

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

Conditions for Running the DTC

•	Vehicle in Service Mode.

•	Ignition voltage is greater than 10 V.

Conditions for Setting the DTC

C012C 01 or C12BA 00

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

C012C 06 or C12B9 00

A short to ground or open is detected signal circuit.

C012C 11, C121A 00, C12F7 00, C128C 00 or C128F 00

Internal sensor failure is detected.

C012C 0F or C12BB 00

Signal is erratic and changes to fast.

Actions Taken when the DTC Sets

•	The ABS indicator turns ON.

•	The red brake indicator turns ON.

•	The traction control/stability control indicator turns ON.

•	The Service Brake Assist and Service StabiliTrak messages are displayed on the driver information centre.

•	The electronic brake control module disables the antilock brake system, the dynamic rear proportioning, the traction control system and the electronic stability program for the duration of the drive cycle.

Conditions for Clearing the DTC

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

•	The history DTC will clear after 40 consecutive fault-free drive cycles have occurred.

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.
Perform the Electronic Brake Control Module Learn procedure with a scan tool.
Verify none of the DTCs listed below are set:

•

DTC C012C

•

DTC C121A

•

DTC C128C

•

DTC C128F

•

DTC C12B9

•

DTC C12BA

•

DTC C12BB

•

DTC C12F7

⇒	*If any of the DTCs are set*

3.1.	Replace the Q5 brake pressure modulator.

3.2.	Verify the DTC does not set while operating the vehicle under the Conditions for Running the DTC.

⇒	If the DTC sets, replace the K17 electronic brake control module.

⇓	If the DTC does not set

3.3.

All OK.

⇓	*If none of the 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