GM Service Manual Online
For 1990-2009 cars only

Circuit Description

This DTC identifies a possible malfunction within the electronic brake control module (EBCM). When the EBCM relay is activated, or turned ON, voltages is supplied to the valve solenoids and pump motor.

Conditions for Setting the DTC

DTC C0056 will set when possible internal malfunctions exist.

Action Taken When the DTC Sets

    • The antilock brake system (ABS) warning lamp is not turned ON.
    • DTC 0056 is stored.
    • The ABS remains functional.

Conditions for Clearing the DTC

    • If the conditions that set DTC C0056 are no longer present, the DTC may be cleared by using the proper scan tool.
    • The DTC that has not occurred in 100 drive cycles will be cleared from history data.

Diagnostic Aids

    • Repair low voltage, driveability, or other electrical complaints first, prior to performing DTC C0056.
    • Make sure the integrity of the connection between the EBCM and the brake pressure modulator valve (BPMV) is secure, tight, and free of corrosion, leaks, and/or damage.
    • Possible cause for DTC C0056 to set is an internal relay problem within EBCM.

Step

Action

Yes

No

1

Did you perform the Diagnostic System Check-ABS?

Go to Step 2

Go to Diagnostic System Check - ABS

2

  1. Install a scan tool.
  2. Turn the ignition ON, with the engine OFF.
  3. Using scan tool, observe DTC information.

Does scan tool display any DTCs set in Current or History Data other than C0056?

Go to Step 3

Go to Step 4

3

Perform the applicable DTC diagnostic for the other DTCs.

Did you find and correct the condition?

System OK

--

4

  1. Turn the ignition switch OFF.
  2. Disconnect the harness from the electronic brake control module (EBCM).
  3. Check the connectors for damage, corrosion, and terminal contact.

Were any problems found?

Go to Step 5

Go to Step 6

5

Repair as needed.

Did you find and correct the condition?

System OK

--

6

Replace the EBCM.

Did you complete the replacement?

System OK

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