With RPO JL4

Antilock Brake System

Diagnostic Information and Procedures

DTC C0279 (W/JL4)

Circuit Description
The EBCM uses the precharge pump in conjunction with the ABS pump to build hydraulic pressure for brake application during a VSES event. Power and ground are both switched ON by the EBCM to energize the precharge pump motor.

Conditions for Running the DTC

- The ignition is ON.
- The precharge pump is activated during a VSES or TCS event or when the EBCM performs the power-up self-test. Refer to ABS Description and Operation (W/O JL4) ABS Description and Operation (W/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 TCS operates with engine torque reduction only.

Conditions for Clearing the DTC

The Conditions for Setting the DTC are no longer present and you use the scan tool Clear DTC's function.

Diagnostic Aids

Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to Testing for Electrical Intermittents, Testing for Intermittent and Poor Connections, Wiring Repairs and Connector Repairs in Wiring Systems.

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.

DTC C0279 (W/JL4) Steps 1 - 3:

DTC C0279 (W/JL4) Continued Steps 4 - 12:

DTC C0279 (W/JL4) Continued Steps 13 - 16: