GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 HUMMER 🢒 2004 🢒 H2 🢒 Brakes 🢒 Antilock Brake System 🢒 ABS Indicator Inoperative

Circuit Description

The instrument panel cluster (IPC) turns the antilock brake system (ABS) indicator ON during the IPC bulb check for approximately 3 seconds when the ignition switch is turned to the ON position. If the electronic brake control module (EBCM) sets a diagnostic trouble code (DTC) the EBCM sends the IPC the command to turn the ABS indicator 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 Inducing Intermittent Fault Conditions in Wiring Systems.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Checks if the scan tool can turn ON and OFF all the indicator lamps in the IPC.

  1. Checks if the circuits going to the IPC or the IPC is at fault.

Step

Action

Yes

No

Schematic Reference: Antilock Brake System Schematics

Connector End View Reference: Instrument Panel, Gages, and Console Connector End Views

1

Did you perform the Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - ABS

2

  1. Using a scan tool, select the Instrument Panel Cluster (IPC) Special Functions mode.
  2. Go to Lamp Test.
  3. In the Lamp Test mode you can turn ON or OFF the instrument panel indicators.

    4. All indicators will turn ON when commanded ON.

Does the antilock brake system (ABS) indicator turn ON then OFF?

Go to Step 3

Go to Step 4

3

Replace the electronic brake control module (EBCM). Refer to Electronic Brake Control Module Replacement .

Is the replacement complete?

Go to Diagnostic System Check - ABS

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4

  1. Disconnect the IPC and connect a Test Light across the appropriate power and ground terminals.
  2. Test Light OFF, repair open in power or ground circuit to IPC.
  3. Test Light ON, check connector for poor connection to the IPC.
  4. If OK, replace the IPC. Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console.

Is the IPC replacement complete?

Go to Diagnostic System Check - ABS

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