With RPO JL4

DTC C0279 (W/ JL4)

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 or traction control system (TCS) event or when the EBCM performs 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 DTCs function.

Diagnostic Aids
Thoroughly inspect connections or circuitry that may cause an intermittent malfunction.

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.