GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2003 🢒 Vibe - AWD 🢒 DTC 🢒 DTC C0278

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 ABS. The valve relay provides power to the antilock brake system (ABS) solenoid valves.

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.

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 in Wiring Systems.

Test Description

The number below refers to the step number on the diagnostic table.

  1. This step determines if the DTC is current.

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

Go to Diagnostic System Check - ABS

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Use the scan tool in order to clear the DTCs.
  4. Using the scan tool, cycle the solenoid valves in the Special Functions menu.
  5. Read the DTCs.

Does the DTC reset?

Go to Step 3

Go to Diagnostic Aids

3

Test The ABS No. 1 fuse for continuity.

Is continuity present?

Go to Step 4

Go to Step 5

4
  1. Test the battery positive voltage circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  2. Test the motor ground circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 7

Go to Step 6

5

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 8

Go to Step 7

6

Replace the brake pressure modulator valve (BPMV). Refer to Brake Pressure Modulator Valve Assembly Replacement .

Did you complete the replacement?

Go to Step 8

--

7

Replace the ABS No. 1 fuse.

Did you complete the replacement?

Go to Step 8

--

5
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK