GM Service Manual Online
For 1990-2009 cars only

Object Number: 365058  Size: MF
ABS Components
Antilock Brake System Schematics Non VE1

Circuit Description

The red BRAKE warning lamp is supplied ignition voltage through the GAUGES fuse. The BRAKE warning lamp can be illuminated by the EBCM, Daytime Running Lights Module (DRL) or Brake Pressure Warning Switch. If a DTC C0288 sets, the EBCM will store in memory but will not disable the ABS. If a DTC C0288 is in memory, the EBCM will not attempt to perform a BRAKE warning lamp bulb check at startup. Also the EBCM will not attempt to use the BRAKE indicator lamp as a backup if the ABS indicator lamp operation is inhibited by a DTC C0286.

Conditions for Setting the DTC

    • High voltage is present on the BRAKE warning lamp circuit when the circuit is expected to be low (lamp commanded on by the EBCM)
    • Anything that keeps the Brake warning lamp circuit high when the lamp is supposed to be illuminated (such as a short to voltage on CKT  33)

Action Taken When the DTC Sets

No action taken, the ABS is not disabled.

Conditions for Clearing the MIL/DTC

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

Diagnostic Aids

DTC C0288 is usually set by a short to voltage in the wiring between the brake warning lamp and the EBCM.

Test Description

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

  1. This step inspects for normal operation of the BRAKE warning lamp.

  2. This step decides between a faulty EBCM, or a short to voltage in circuit 680.J 36169-A .

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 RUN.
  2. Observe the BRAKE warning lamp operation.

Did the BRAKE warning lamp turn on and then turn off after 2 seconds?

--

Go to Step 5

Go to Step 3

3

  1. Turn the ignition to OFF.
  2. Disconnect the 10-way EBCM harness connector from the EBCM.
  3. Using a J 36169-A with a 3 amp fuse, connect terminal H of the 10-way EBCM harness connector to ground.
  4. Turn ignition to RUN.

Does the BRAKE warning lamp turn on?

--

Go to Step 6

Go to Step 4

4

Inspect the jumper wire fuse.

Is the fuse open?

--

Go to Step 7

Go to Step 5

5

Malfunction is intermittent.

  1. Inspect all connectors and harnesses for damage which may result in high resistance when all components are connected.
  2. Perform all necessary repairs.

Is Repair complete?

--

Go to Diagnostic System Check - ABS

Malfunction is intermittent. Go to Diagnostic Aids

6

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

Is repair complete?

--

Go to Diagnostic System Check - ABS

--

7

Repair a short to voltage in CKT 680.

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--