Circuit Description
The valve relay is part of the electronic brake control module (EBCM). The EBCM turns ON the valve relay when the ignition switch is in the ON position and no malfunction exists in the Antilock Brake System (ABS). The valve relay provides power to the ABS solenoid valves.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0278 Solenoid Relay Circuit Open or Shorted
Conditions for Running the DTC
DTC C0278 can be set anytime the ignition switch is turned to the ON position.
Conditions for Setting the DTC
The EBCM detects that the valve relay is OFF when actually the EBCM commanded the valve relay ON.
Action Taken When the DTC Sets
| • | The ABS is disabled. |
| • | The ABS warning indicator turns ON. |
| • | The traction control and vehicle stability control (VSC) is disabled, if equipped. |
| • | The VSC warning indicator turns ON, if equipped. |
Conditions for Clearing the DTC
The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.
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:
| • | An open or high resistance in the battery positive voltage circuit |
| • | An open or high resistance in the motor ground circuit |
| • | An internal EBCM malfunction |
If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections .
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics Connector End View Reference: Antilock Brake System Connector End Views | ||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||
Does the DTC reset? | -- | Go to Step 3 | Go to Diagnostic Aids | |||||||
3 |
Does the voltage measure as specified? | 10-14 V | Go to Step 4 | Go to Step 5 | ||||||
4 | Measure the resistance between the EBCM ground circuits and a good ground. Does the resistance measure as specified? | Below 1 ohms | Go to Step 7 | Go to Step 6 | ||||||
5 | Locate and repair the following in the battery positive voltage circuit.
Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 8 | -- | ||||||
6 | Locate and repair the open or high resistance in the motor ground circuit. Refer to Circuit Testing and Wiring Repairs Did you find and correct the condition? | -- | Go to Step 8 | -- | ||||||
7 | Replace the brake pressure modulator valve (BPMV). Refer to Brake Pressure Modulator Valve Assembly Replacement . Did you complete the replacement? | -- | Go to Step 8 | -- | ||||||
8 |
Does the DTC reset? | -- | Go to Step 2 | System OK | ||||||
