DTC C012A, C128B, C128E, or C12B2-C12B4
Diagnostic Instructions
DTC Descriptors
DTC C012A 00: Brake Master Cylinder Pressure Sensor Malfunction
DTC C128E 00: ABS Master Cylinder Pressure Sensor Raw Offset Error
DTC C012A 01: Brake Master Cylinder Pressure Sensor Low Voltage/Open
DTC C12B3 00: ABS Master Cylinder Pressure Sensor Circuit Short To Battery
DTC C012A 06: Brake Master Cylinder Pressure Sensor Short to Ground or Open
DTC C12B2 00: ABS Master Cylinder Pressure Sensor Circuit Open or Short To Ground
DTC C012A 11: Brake Master Cylinder Pressure Sensor High Input
DTC C128B 00: ABS Master Cylinder Pressure Sensor Offset Error
DTC C012A 0F: Brake Master Cylinder Pressure Sensor Signal Erratic
DTC C12B4 00: ABS Master Cylinder Pressure Sensor Performance
Circuit/System Description
The electronic brake control module 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.
Conditions for Running the DTC
| • | The brake pedal is not applied. |
| • | Ignition voltage is greater than 10 V. |
| • | Vehicle ON or Vehicle in Service Mode. |
Conditions for Setting the DTC
C012A 00, C128E 00 or C128B 00
| • | The Electronic Brake Control Module Learn was not successful. |
| • | 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. |
C012A 01 or C12B3 00
A short to battery is detected on the sensor signal circuit.
C012A 06 or C12B2 00
A short to ground or open is detected on the sensor signal circuit.
C012A 11
Improper learn procedure performed.
C012A 0F or C12B4 00
The signal is erratic and changes to fast.
Action 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 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
Schematic Reference
Antilock Brake System Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
ABS Description and Operation
Electrical Information Reference
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:
| ⇒ | If any of the DTCs are set |
| 3.1. | Replace 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 K17 electronic brake control module. |
| ⇓ | If the DTC does not set |
| ⇓ | If none of the DTCs are set |
- All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
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