GM Service Manual Online
For 1990-2009 cars only

Object Number: 554424  Size: MF
ABS Components
EBCM Power Supply and Communication

Circuit Description

The Instrument Panel Cluster (IPC) turns the ABS Indicator lamp ON at bulb check for approximately 2 seconds when the ignition switch is turned to the ON position. Afterwards, the EBCM sends a class 2 message the IPC which commands the ABS indicator lamp OFF. If the EBCM sets a Diagnostic Trouble Code (DTC), the EBCM sends a class 2 message to the IPC to command the ABS indicator lamp ON.

Diagnostic Aids

    • It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
    • Thoroughly inspect any circuitry that may be causing the complaint for the following conditions:
       - Backed out terminals
       - Improper mating
       - Broken locks
       - Improperly formed or damaged terminals
       - Poor terminal-to-wiring connections
       - Physical damage to the wiring harness
    • The following conditions may cause an intermittent malfunction:
       - A poor connection
       - Rubbed-through wire insulation
       - A broken wire inside the insulation
    • If an intermittent malfunction exists refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  1. The EBCM turns Off the ABS and BRAKE indicator lamps after bulb test. This step shows the EBCMs ability turn off the BRAKE indicator lamp.

ABS Indicator On with No DTC Set

Step

Action

Value(s)

Yes

No

DEFINITION: ABS indicator does not turn OFF after the Instrument Panel Cluster (IPC) bulb check and no ABS DTC(s) are set.

Notice: Refer to ABS Operation in the Preface section.

1

Was the ABS Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check

2

  1. Turn the Ignition Switch to OFF, then ON.
  2. Observe the red BRAKE Lamp during IPC bulb check.

Does the red BRAKE Lamp turn ON, then OFF after approximately 2 seconds?

--

Go to Step 3

Go to Step 7

3

Using a scan tool from the Instrument Panel Cluster Special Functions menu, attempt to turn the ABS Lamp OFF.

Does the ABS indicator turn OFF when commanded?

--

Go to Step 4

Go to Step 6

4

  1. Scan tool still connected.
  2. Turn the Ignition Switch to OFF, then to ON.
  3. Observe the IPC bulb check

Does the ABS Lamp turn ON , then OFF after approximately 2 seconds

--

Go to Testing for Intermittent Conditions and Poor Connections in wiring systems

Go to Step 5

5

Using a scan tool from the 4WAL 3 Sensor (ABS) Special Functions menu, attempt to turn the ABS Lamp OFF.

Does the ABS indicator turn OFF when commanded?

--

Go to Step 6

Go to Step 7

6

Replace the Instrument Panel Cluster. Refer to Instrument Cluster Replacement .

Is the replacement complete?

--

Go to Diagnostic System Check

--

7

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

Is the replacement complete?

--

Go to Diagnostic System Check

--