Circuit Description
The EBCM applies ground to the brake lamp relay control circuit in order to energize the ABS indicator lamp relay and turn OFF the ABS indicator.
Diagnostic Aids
Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to the following:
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests if the EBCM is illuminating the ABS indicator.
-
This step tests the ABS indicator failure control circuit for a short to ground by substituting the Instrument Panel Cluster (IPC) and the ABS indicator lamp with a test lamp while leaving the ABS indicator lamp relay disconnected.
-
This step simulates the EBCM commanding the ABS indicator OFF.
-
The EBCM may be damaged if the brake lamp relay control circuit is shorted to voltage.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Air Antilock Brake System Schematics | |||
1 | Did you perform the Air ABS Diagnostic System Check? | Go to Step 2 | |
2 |
Does the ABS indicator turn ON for approximately 7 seconds, turn OFF, blink ON and OFF twice and then remain OFF? | Go to Diagnostic Aids | Go to Step 3 |
Does the ABS indicator turn ON for approximately 7 seconds, turn OFF, blink ON and OFF twice and then remain ON? | Go to Step 13 | Go to Step 4 | |
4 | Disconnect the ABS indicator lamp relay. Does the ABS indicator turn OFF? | Go to Step 7 | Go to Step 5 |
Does the test lamp illuminate? | Go to Step 6 | Go to Step 14 | |
6 | 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 | -- |
7 | Connect a test lamp between the ignition 1 voltage circuit at the ABS lamp relay harness connector and a good ground. Does the test lamp illuminate? | Go to Step 9 | Go to Step 8 |
8 | Repair the open in the ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 17 | -- |
Does the ABS indicator turn OFF? | Go to Step 13 | Go to Step 10 | |
Test the brake lamp relay control circuit for an open or a short to voltage. Refer to Circuit Testing or Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 17 | Go to Step 11 | |
11 | Inspect for poor connections at the harness connector of the ABS indicator 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 12 |
12 | Replace the ABS indicator lamp relay. Did you complete the replacement? | Go to Step 17 | -- |
13 | 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 |
14 | Inspect for poor connections at the harness connector of the IPC. 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 15 |
15 | 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 | -- |
16 |
Important: Following EBCM replacement, perform the EBCM self-configuration procedure. Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Did you complete the replacement? | Go to Step 17 | -- |
17 |
Does the ABS indicator turn ON for approximately 7 seconds, turn OFF, blink ON and OFF twice and then remain OFF? | System OK | Go to Step 3 |
