For 1990-2009 cars only
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 00: Master Cylinder Pressure SensorDTC 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 (VSES) event. The master cylinder pressure sensor is internal to the brake pressure modulator valve (BPMV).
Conditions for Running the DTC
| • | Ignition ON. |
| • | Ignition voltage is greater than 10 volts. |
| • | The brake pedal is not applied. |
Conditions for Setting the DTC
C012A 00, C128E, C012A 11 or C128B
Internal sensor failure is detected.
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 (VSES) for the duration of the ignition cycle. |
| • | A DIC 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
Connector End View Reference
Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Verify that DTC C012A, C128B, C128E, C12B2, C12B3, or C12B4 is not set.
| ⇒ | If DTC is set replace EBCM/brake pressure modulator valve (BPMV) assembly. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for EBCM replacement, setup, and programming |
