C0279

DTC C0279

Circuit Description

The electronic brake control module (EBCM) uses the precharge pump in conjunction with the ABS pump to build hydraulic pressure for brake application during a vehicle stability enhancement system (VSES) event. Power and ground are both switched ON by the EBCM to energize the precharge pump motor.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0279 Pre-charge Pump Circuit Performance

Conditions for Running the DTC

^ The ignition is ON.
^ The precharge pump is activated during a VSES event or when the EBCM performs the power-up self-test. Refer to ABS Description and Operation (W/JL4) ABS Description and Operation (W/O JL4) for a complete description of the power-up self-test.

Conditions for Setting the DTC

^ The EBCM detects open precharge pump circuitry.
^ The EBCM detects shorted precharge pump circuitry.
^ The master cylinder pressure sensor signal does not increase sufficiently during a pressure-build event.

Action Taken When the DTC Sets

^ The EBCM disables the VSES.
^ The stability indicator turns ON.

Conditions for Clearing the DTC

The conditions for setting the DTC are no longer present and you use the scan tool Clear DTCs function.

Diagnostic Aids

Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to the following:

^ Testing for Electrical Intermittents
^ Testing for Intermittent Conditions and Poor Connections
^ Wiring Repairs
^ Connector Repairs

Test Description

The numbers below refer to the step numbers on the diagnostic table.
3. This step tests if the EBCM is detecting open or shorted precharge pump motor circuitry.
4. This step tests if the EBCM is capable of energizing the precharge pump motor.

Step 1 - Step 8:

Step 9 - Step 14:

Step 15 - Step 16: