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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 Savana 🢒 Body and Accessories 🢒 Instrument Panel, Gauges, and Console 🢒 ABS Indicator Always On

ABS Indicator Always On Domestic

Circuit Description

The EBCM illuminates the ABS indicator by supplying ground to the lamp . When the ABS indicator is commanded ON, the feedback voltage to the EBCM from the ABS indicator failure control circuit is low.

Diagnostic Aids

Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to the following:

    •  Testing for Electrical Intermittents
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs
    •  Connector Repairs

Test Description

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

  1. This step tests if the EBCM is applying ground to the ABS indicator lamp.

    2.

  2. This step tests the ABS indicator failure control circuit for a short to ground by substituting the instrument panel cluster and the ABS indicator lamp with a test lamp while leaving the EBCM disconnected.

Step

Action

Yes

No

Schematic Reference: Antilock Brake System Schematics

1

Did you perform the ABS Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - ABS

2
  1. Turn OFF the ignition for 5 seconds.
  2. Turn ON the ignition while observing the ABS indicator.

Does the ABS indicator illuminate for 2 seconds and then turn OFF?

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the 10-way EBCM harness connector.
  3. Turn ON the ignition.

Does the ABS indicator illuminate?

Go to Step 4

Go to Step 7

4

  1. Turn OFF the ignition.
  2. Remove the instrument panel cluster (IPC). Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console.
  3. Connect a test lamp between the ignition 1 voltage circuit and the ABS indicator failure control circuit.
  4. Turn ON the ignition.

Does the test lamp illuminate?

Go to Step 5

Go to Step 6

5

Repair the short to ground in the ABS indicator failure control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 8

--

6

Replace the instrument panel cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console.

Did you complete the replacement?

Go to Step 8

--

7

Important: Following EBCM replacement, use the scan tool to perform the Tire Size Calibration procedure.

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

Did you complete the replacement?

Go to Step 8

--

8
  1. Turn OFF the ignition for 5 seconds.
  2. Turn ON the ignition while observing the ABS indicator.

Does the ABS indicator illuminate for 2 seconds and then turn OFF?

System OK

Go to Step 3

ABS Indicator Always On Export

Circuit Description

The EBCM illuminates the ABS indicator by supplying ground to the lamp. When the ABS indicator is commanded ON, the feedback voltage to the EBCM from the ABS indicator failure control circuit is low. The ABS indicator also illuminates if the ground circuit between EBCM and the electronic brake control lamp relay is open.

Diagnostic Aids

Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to the following:

    •  Testing for Electrical Intermittents
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs
    •  Connector Repairs

Test Description

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

  1. A malfunction which illuminates the red brake warning indicator also illuminates the ABS indicator.

    2.

  2. This step tests if the electronic brake control lamp relay is applying ground to the ABS indicator lamp.

    3.

  3. This step tests if the EBCM is applying ground to the ABS indicator lamp.

    4.

  4. This step tests the ABS indicator failure control circuit for a short to ground by substituting the instrument panel cluster and the ABS indicator lamp with a test lamp while leaving the EBCM disconnected.

Step

Action

Yes

No

Schematic Reference: Antilock Brake System Schematics

1

Did you perform the ABS Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - ABS

2
  1. Turn OFF the ignition for 5 seconds.
  2. Turn ON the ignition while observing the ABS indicator.

Does the ABS indicator illuminate for 2 seconds and then turn OFF?

Go to Diagnostic Aids

Go to Step 3

3

Is the brake warning indicator also always ON?

Go to Brake Warning Indicator Always On in Hydraulic Brakes

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Remove the electronic brake control lamp relay from the underhood fuse-relay center.
  3. Turn ON the ignition while observing the ABS indicator.

Does the ABS indicator illuminate for 2 seconds and then turn OFF?

Go to Step 7

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Disconnect the 10-way EBCM harness connector.
  3. Turn ON the ignition while observing the ABS indicator.

Does the ABS indicator illuminate?

Go to Step 6

Go to Step 16

6

  1. Turn OFF the ignition.
  2. Remove the instrument panel cluster (IPC). Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console.
  3. Connect a test lamp between the ignition 1 voltage circuit and the ABS indicator failure control circuit at the instrument panel cluster harness connector.
  4. Turn ON the ignition.

Does the test lamp illuminate?

Go to Step 8

Go to Step 14

7

Connect a test lamp between the ignition 3 voltage circuit in the underhood fuse-relay center and a good ground.

Does the test lamp illuminate?

Go to Step 10

Go to Step 9

8

Repair the short to ground in the ABS indicator failure control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 17

--

9

Repair the open in the ignition 3 voltage circuit. Refer to Wiring Repairs in Wiring systems.

Did you complete the repair?

Go to Step 17

--

10

Connect a test lamp between battery positive voltage and the ground circuit of the electronic brake control lamp relay coil.

Does the test lamp illuminate?

Go to Step 12

Go to Step 11

11
  1. Turn OFF the ignition.
  2. Disconnect the 10-way EBCM harness connector.
  3. Test the ground circuit of the electronic brake control lamp relay coil for an open. Refer to Circuit Testing and Wiring Repairs in Wiring systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 15

12

Inspect for poor connections at the electronic brake control lamp relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 13

13

Replace the electronic brake control lamp relay.

Did you complete the replacement?

Go to Step 17

--

14

Replace the instrument panel cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console.

Did you complete the replacement?

Go to Step 17

--

15

Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 16

16

Important: Following EBCM replacement, use the scan tool to perform the Tire Size Calibration procedure.

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

Did you complete the replacement?

Go to Step 17

--

17
  1. Turn OFF the ignition for 5 seconds.
  2. Turn ON the ignition while observing the ABS indicator.

Does the ABS indicator illuminate for 2 seconds and then turn OFF?

System OK

Go to Step 3