C012E
DTC C012E or C12FE
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 C012E 00
- Hydraulic Brake Boost Pressure Loss
DTC C12FE 00
- ABS Pump Pressure Loss
Circuit/System Description
The electronic brake control module (EBCM) 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. The boost control function will keep operating amongst conditions that cause the boost pressure to be limited to less than commanded. The boost control continues to apply until the boost pressure available is no greater than the master cylinder pressure the driver is applying.
Conditions for Running the DTC
* Engine Running
* Ignition voltage is greater than 10 volts.
* Transmission in Park
* Brake pedal was applied.
Conditions for Setting the DTC
* Boost pressure command greater than boost pressure +1500 kPa (217 psi) for 250 ms.
* Master cylinder pressure greater than boost pressure -200 kPa (29 psi) for 250 ms.
* Accumulator pressure greater than 16,000 kPa (2320 psi) for 250 ms.
* DTCs C12BC, C12BD, C12BE, C128A, C128D, C127D, C12E4, C1255, C1256, C126E, C123C, or C127C not set.
Action Taken When the DTC Sets
* The EBCM disables the ABS, traction control system and the 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.
Diagnostic Aids
* Excessive brake pedal applies (10 or more applies in 30 seconds) can cause the DTC to set.
* The DTC can set if the ignition key is in the Accessory position, the brake pedal is applied and then the ignition key is turned ON.
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
Note: The battery must be able to maintain a charge during this procedure. It is recommended that a charger/maintainer or equivalent be used to maintain proper battery voltage during this procedure.
1. Verify that no other EBCM DTCs are set.
• If DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
2. Ignition ON, engine OFF, using a scan tool access the EBCM, Module Setup screen, and perform the EBCM Relearn. The relearn procedure will verify valve and pressure sensor calibrations are correct.
Note: To ensure the complete brake modulator and high pressure accumulator pressure relief procedure is allowed to occur; the brake controller must see one brake pedal apply with the engine running followed by a proper shutdown without applying the brake pedal.
3. Transmission in PARK, engine running, apply and release the brake pedal.
Note: The ignition must transition to the OFF position without pausing at ACCESSORY and without applying the brake pedal. This ensures that the brake modulator and high pressure accumulator relief occurs. This process will take approximately 1-2 minutes.
4. Ignition OFF, key removed from the ignition, wait 2 minutes.
Note: The ignition must remain in the ON position with the engine OFF during the following steps.
5. Ignition ON, brake pedal released, verify the following EBCM scan tool parameters are within the specified range:
* BMC Prim. Piston Pos. Sen. 5 V Reference Position - Between 4.75-5.25 V
* BMC Primary Piston Position Sensor A - Between 0.4-0.8 V
* BMC Primary Piston Position Sensor B - Between 4.2-4.6 V
• If any of the parameters are not within the specified range, refer to DTC C0277, C120C, C129A, C129B, C129D, C129E, C12B1, or C12F8 Antilock Brake System - Hybrid.
6. Brakes not applied, verify the following EBCM scan tool parameters are within the specified range:
* Master Cylinder Pressure Sensor Input - Less than 100 kPa (15 psi)
* Rear Brake Pressure Sensor - Less than 100 kPa (15 psi)
* Brake Pressure Sensor Input - Less than 100 kPa (15 psi)
* Accum. Pressure Sensor - Less than 800 kPa (116 psi)
• If any of the parameters are not within the specified range, replace the brake pressure modulator valve.
7. Perform a hydraulic check, refer to Brake Hydraulic and Assist System Diagnosis (Two-mode Hybrid) Brake Hydraulic and Assist System Diagnosis (Two-mode Hybrid).
8. If the Brake Hydraulic and Assist System tests normal, replace the brake pressure modulator valve and verify DTC does not reset. If the DTC resets, replace the 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, relearn, and programming