GM Service Manual Online
For 1990-2009 cars only

Object Number: 568167  Size: SF
ABS Components
Antilock Brake System Schematics

Circuit Description

This DTC identifies a malfunction within the EBCM.

Conditions for Setting the DTC

    • DTC C1256xx can be set when there is a solenoid short to battery inside the BPMV. If DTCs C1261 - C1274 are set along with C1256xx then pursue the solenoid DTCs first.
    • DTC C1256xx can be set when there is an internal EBCM malfunction.

Action Taken When the DTC Sets

A malfunction DTC is stored, ABS/TCS/Active Handling (RPO JL4) are not disabled and the ABS and Car Icon (TCS indicator) are not turned on.

Conditions for Clearing the DTC

    • Condition for DTC is no longer present and scan tool clear DTC function is used.
    • Fifty ignition cycles have passed with no DTCs detected.

Diagnostic Aids

    • When DTC C1256xx is displayed on the Scan Tool, it will be followed by two more numbers which should be noted along with any other DTCs that may be displayed. The additional two numbers displayed with DTC C1256xx are for aiding engineering to determine the cause of the internal malfunction.
    • Make sure the integrity of the connection between the EBCM and the BPMV is secure, tight, and free from corrosion.

DTC C1256 EBCM Internal Malfunction

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2

Are any valve solenoid DTC(s) present (C1261 - C1274)?

--

Go to Applicable DTC Table. Go to Diagnostic Trouble Code (DTC) List/Type

Go to Step 3

3

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the EBCM.
  3. Check for damaged, pushed out, or miswired terminals.

Was any damage found?

--

Go to Step 4

Go to Step 5

4

Repair as necessary.

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

5

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

Is the replacement complete?

--

Go to Diagnostic System Check - ABS

--