C12B2

DTC C012A, C128B, C128E, or C12B2-C12B4

Diagnostic Instructions

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

DTC Descriptors
DTC C012A 00
- Master Cylinder Pressure Sensor

DTC C128E
- Master Cylinder Pressure Sensor

DTC C012A 01
- Master Cylinder Pressure Sensor Short to Battery

DTC C12B3
- Master Cylinder Pressure Sensor Short to Battery

DTC C012A 06
- Master Cylinder Pressure Sensor Short to Ground or Open

DTC C12B2
- Master Cylinder Pressure Sensor Short to Ground or Open

DTC C012A 11
- Master Cylinder Pressure Sensor Above Maximum Threshold

DTC C128B
- Master Cylinder Pressure Sensor Above Maximum Threshold

DTC C012A 0F
- Master Cylinder Pressure Sensor Erratic

DTC C12B4
- Master Cylinder Pressure Sensor Erratic

Circuit/System Description

The electronic brake control module (EBCM) uses input from the master cylinder pressure sensor for more accurate control during a vehicle stability enhancement system event. The master cylinder pressure sensor is internal to the brake pressure modulator valve.

Conditions for Running the DTC

* The ignition is ON.
* Ignition voltage is greater than 10 volts.
* The brake pedal is not applied.

Conditions for Setting the DTC

C012A 00, C128E or C128B

Internal sensor failure is detected.

C012A 11

Improper relearn performed

C012A 01 or C12B3

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

C012A 06 or C12B2

A short to ground or open is detected signal circuit.

C012A OF or C12B4

Signal is erratic and changes faster than physically allowed.

Action Taken When the DTC Sets

* The EBCM disables the ABS and vehicle stability enhancement system for the duration of the ignition cycle.
* A driver information center 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 EBCM clears the history DTC when a current DTC is not detected in 40 consecutive drive cycles.

Reference Information
Schematic Reference

Antilock Brake System Schematics [1][2]Antilock Brakes / Traction Control Systems
Connector End View Reference

Component Connector End Views Connector Views
Description and Operation

ABS Description and Operation Description and Operation
Electrical Information Reference

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

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. Using a scan tool, perform the EBCM, Module Setup, EBCM Relearn.
2. Verify that DTC C012A, C128B, C128E, C12B2, C12B3, or C12B4 is not set.

• If the DTC is set replace brake pressure modulator valve assembly. If the DTC resets, replace EBCM.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Brake Pressure Modulator Valve Replacement Service and Repair
* Control Module References Control Module References for EBCM replacement, setup, and programming