GM Service Manual Online
For 1990-2009 cars only

Object Number: 175132  Size: SF
ABS Components
Antilock Brake System Schematics

Circuit Description

The ABS is capable of operating with different brake types and different wheel bases from several different vehicle configurations. All vehicles are pre-programmed from the factory with the proper trim level calibration. The trim level calibration corresponds to the different wheel bases and brake types available on each vehicle. Whenever the EBCM is replaced and/or the wheel base is increased or decreased, it is necessary to set the trim level calibration in the EBCM. It will be necessary to obtain the wheel base and type of brakes (using RPO codes) to select the correct trim level on the Scan Tool. Once programmed , this calibration will remain even if the battery is disconnected or the EBCM is removed from the vehicle. Refer to Trim Level Calibration, in ABS Description .

Conditions for Setting the DTC

EBCM installed on vehicle without trim level calibration.

Action Taken When the DTC Sets

    • The ABS indicator lamp is turned on.
    • The ABS is disabled.

Conditions for Clearing the DTC

    • Repair the conditions responsible for setting the DTC.
    • Use the Scan Tool Clear DTCs function.

Diagnostic Aids

If any other DTCs are set, Repair those DTCs first. If no other DTCs are set, ensure that the correct trim level is set using the Scan Tool. Refer to Trim Level Calibration, in ABS Description .

Test Description

The numbers below refer to the steps in the diagnostic table:

  1. This step checks for an EBCM trim level calibration.

  2. This step checks for the correct EBCM trim level calibration.

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2

Using the Scan Tool , read the current trim calibration level within the EBCM. Refer to Trim Level Calibration in ABS Description .

Is the trim level calibration correct for the vehicle?

--

Go to Step 3

Go to Step 5

3

  1. Using the Scan Tool , clear all DTCs.
  2. Test drive the vehicle above 16 km/h (10 mph).

  3. Does the DTC C0279 set as a current DTC?

--

Go to Step 4

Go to Diagnostic Aids

4

Replace the EBCM. Refer to Electronic Brake Control Module Replacement

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

5

Using the Scan Tool , calibrate the EBCM with the correct trim level. Refer to Trim level Calibration in ABS Description .

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--