C12B6

DTC C012B or C12B6-C12B8

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (with HP2) (Initial Inspection and Diagnostic Overview)Diagnostic System Check - Vehicle (without HP2) (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.

DTC Descriptors
DTC C012B 01
- High Pressure Accumulator Pressure Sensor Short to Battery

DTC C12B7
- High Pressure Accumulator Pressure Sensor Short to Battery

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

DTC C12B6
- High Pressure Accumulator Pressure Sensor Short to Ground or Open

DTC C012B 0F
- High Pressure Accumulator Pressure Sensor Erratic

DTC C12B8
- 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 2500 psi for use in apply 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 (VSES) event.The high pressure accumulator sensor is internal to the brake pressure modulator valve (BPMV).

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 OF 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 (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 (Electrical Diagrams)
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 (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

1. Perform the EBCM, module setup, EBCM Relearn
2. Verify that DTC C012B, C12B7, C12B6, C12B8 is not set.

If DTC is set replace brake pressure modulator valve (BPMV) assembly. If any of the DTCs 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 (Programming and Relearning) for EBCM replacement, setup, and programming