GM Service Manual Online
For 1990-2009 cars only

Object Number: 155116  Size: SF

Circuit Description

DTC C1255 identifies an internal malfunction detected by the EBCM/EBTCM ABS motor driver interface, custom integrated circuit.

Action Taken When the DTC Sets

    • A malfunction DTC stores.
    • The ABS/TCS disables.
    • The amber ABS/TCS warning indicators turn on.
    • The red BRAKE warning indicator turns on if the rear piston in the ABS brake motor pack is not in the home piston.

Conditions for Clearing the DTC

    • The condition responsible for setting the DTC no longer exists and the Scan Tool Clear DTC function is used.
    • 100 drive cycles pass with no DTC detected.

Diagnostic Aids

The following conditions may cause an intermittent malfunction:

    • A poor connection
    • Rubbed-through wire insulation
    • A broken wire inside the insulation

Use the enhanced diagnostic function of the Scan Tool in order to measure the frequency of the malfunction. Refer to the Scan Tool manual or Scan Tool Diagnostics located in this section for the procedure.

Thoroughly inspect any circuitry that may be causing the intermittent complaint for the following conditions:

    • Backed out terminals
    • Improper mating
    • Broken locks
    • Improperly formed or damaged terminals
    • Poor terminal-to-wiring connections
    • Physical damage to the wiring harness

Clear the DTCs after completing the diagnosis. Test drive the vehicle for three drive cycles in order to verify that the DTC does not reset. Use the following procedure in order to complete one drive cycle:

  1. Start the vehicle.
  2. Drive the vehicle over 16 km/h (10 mph).
  3. Stop the vehicle.
  4. Turn the ignition to the OFF position.

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2

  1. Install a scan tool.
  2. Turn the ignition switch to the RUN position, engine off.
  3. Use the scan tool in order to read the DTCs.

Is DTC C1255 set as a current DTC?

--

Go to Step 3

Go to Step 5

3

  1. Use the scan tool in order to clear the DTCs.
  2. Test drive the vehicle for three drive cycles.
  3. Use the scan tool in order to look for DTCs.

Does DTC C1255 set as a current DTC?

--

Go to Step 4

Go to Step 5

4

Replace the EBCM/EBTCM. Refer to Electronic Brake and Traction Control Module Replacement .

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

5

The malfunction is intermittent or not present at this time.

Is a concern still present?

--

Go to Diagnostic Aids

Go to Diagnostic System Check - ABS