C12B6

DTC C012B or C12B6-C12B8

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 C012B 01
- High Pressure Accumulator Pressure Sensor Short to Battery

DTC C12B7
- ABS High Pressure Accumulator Pressure Sensor Circuit Short to Battery

DTC C012B 06
- High Pressure Accumulator Pressure Sensor Short to Ground or Open

DTC C12B6
- ABS High Pressure Accumulator Pressure Sensor Circuit Open or Short To Ground

DTC C012B 0F
- High Pressure Accumulator Pressure Sensor Erratic

DTC C12B8
- ABS High Pressure Accumulator Pressure Sensor Erratic

Circuit/System Description

The high pressure accumulator is attached to the brake pressure modulator valve and provides up to 18,000 kPa (2,600 psi) for use when applying the brakes. The electronic brake control module (EBCM) uses input from the high pressure accumulator sensor for more accurate control during braking and vehicle stability enhancement system event. The high pressure accumulator sensor is internal to the brake pressure modulator valve assembly.

Conditions for Running the DTC

* Ignition ON.
* Ignition voltage is greater than 10 volts.

Conditions for Setting the DTC

C012B 01 or C12B7

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

C012B 06 or C12B6

A short to ground or open is detected on signal circuit.

C012B 0F or C12B8

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 Hybrid/EV Battery Pack X1 A4
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, Configuration/Reset Functions, EBCM Relearn.
2. Verify that DTC C012B, C12B6, C12B7, C12B8 is not set.

If the DTC is set replace Q5 brake pressure modulator valve assembly and verify the DTC does not reset. If the DTC resets, replace the K17 EBCM.

Repair Instructions

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

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