GM Service Manual Online
For 1990-2009 cars only

Circuit Description

This DTC identifies a malfunction within the electronic brake control module (EBCM).

Conditions for Running the DTC

The ABS conditions and the braking conditions are normal.

Conditions for Setting the DTC

An internal EBCM malfunction exists.

Action Taken When the DTC Sets

If equipped, the following actions occur:

    • The EBCM disables the DRP/ABS/TCS/VSES for the duration of the ignition cycle.
    • The ABS indicator turns ON.
    • The TRACTION CONTROL indicator turns ON.
    • The red BRAKE warning indicator turns ON.
    • The DIC displays the SERVICE STABILITY SYS message.
    • For some DTC C1255xx, the EBCM disables the variable effort steering (VES) for the duration of the ignition cycle and the DIC displays the SERVICE STEERING SYS message.

Conditions for Clearing the DTC

    • The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
    • The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids

    • The scan tool displays 2 additional characters after the DTC. Take note of the 2 character code and any other DTCs that are set. The 2 character code is an engineering aid used in order to determine the cause of the internal malfunction.
    • When the scan tool displays DTC C1255m3, the EBCM has not been programmed. Perform the setup procedure for the EBCM.

Test Description

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

  1. This step determines whether the DTC is current.

Step

Action

Value(s)

Yes

No

1

Did you perform the ABS Diagnostic System Check?

--

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. With the scan tool, perform the Automated Test.

Does the DTC reset as a current DTC?

--

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

3

Important: Perform the setup procedure for the EBCM. An unprogrammed EBCM will result in the following conditions:

   • Inoperative or poorly functioning DRP/ABS/TCS/VSES/VES (if equipped)
   • Set DTC C1248 EBCM Turned the Red Brake Warning Indicator On
   • Set DTC C1255m3 EBCM Internal Malfunction

Replace the EBCM. Refer to Electronic Brake Control Module Replacement .

Did you complete the repair?

--

Go to Step 4

--

4

  1. Use the scan tool in order to clear the DTCs.
  2. With the scan tool, perform the Automated Test.

Does the DTC reset?

--

Go to Step 2

System OK