GM Service Manual Online
For 1990-2009 cars only

Object Number: 363885  Size: MF
ABS Components
Antilock Brake System Schematics

Circuit Description

The EBCM controls the ABS indicator lamp illumination by supplying a ground to the EBCM 10-way terminal B. When the vehicle is started or the ignition is turned to the RUN position, the ABS indicator should illuminate for two seconds and turn off.

Diagnostic Aids

If the ABS indicator lamp is on always with no DTCs set (never turns off after two seconds with the vehicle started or with the ignition switch in the RUN position), there is a short to ground in CKT 867 between the instrument cluster and the EBCM or the EBCM is internally shorted to ground.

Test Description

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

  1. This step checks for a short to ground in CKT 867.

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. Turn the ignition to OFF.
  2. Disconnect the 10-way EBCM harness connector from the EBCM.
  3. Turn the ignition to RUN.

Does the ABS indicator lamp turn on?

--

Go to Step 3

Go to Step 4

3

Repair the short to ground in CKT 867.

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

4

  1. Inspect CKT 867 and the 10-way EBCM harness connector for physical damage which may result in a short to ground with the 10-way EBCM harness connector connected to the EBCM.
  2. Reconnect all the connectors.
  3. Clear all the DTCs using the scan tool.
  4. Test drive the vehicle above 16 km/h (10 mph).

Is the ABS indicator lamp on constantly?

--

Go to Step 5

Go to Diagnostic Aids

5

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

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--