Circuit Description
The pump motor relay is part of the electronic brake control module (EBCM). The EBCM turns ON and OFF the pump motor relay as deemed necessary in order to activate the pump motor. The pump motor modulates brake hydraulic pressure during an antilock brake system (ABS) stop.
Conditions for Running the DTC
DTC C0274 can be set anytime the ignition switch is in the ON position.
Conditions for Setting the DTC
The electronic brake control module (EBCM) detects an short in the pump motor circuitry.
Action Taken When the DTC Sets
| • | The ABS is disabled. |
| • | The ABS warning indicator turns ON. |
Conditions for Clearing the DTC
| • | The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used. |
| • | After the DTC is cleared, the ABS indicator will remain ON until the vehicle is road tested to verify the repair. Once the vehicle has been driven at a speed above 16 km/h (10 mph) for 20 seconds with no malfunctions present, the EBCM will turn OFF the ABS indicator. |
Diagnostic Aids
Thoroughly inspect the wiring and the connectors. An incomplete inspection of the wiring and the connectors may result in a misdiagnosis, causing a part replacement with the reappearance of the malfunction.
The following are possible causes of the malfunction:
| • | A short to ground in the battery positive voltage circuit |
| • | An internal EBCM malfunction |
If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics Connector End View Reference: Antilock Brake System Connector End Views | |||
1 | Did you perform A Diagnostic System Check - ABS? | Go to Step 2 | |
Does the DTC reset? | Go to Step 3 | Go to Diagnostic Aids | |
3 | Test the battery positive voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 5 | Go to Step 4 |
4 | Replace the brake pressure modulator valve (BPMV). Refer to Brake Pressure Modulator Valve Assembly Replacement . Did you complete the replacement? | Go to Step 5 | -- |
5 |
Does the DTC reset? | Go to Step 2 | System OK |
