Circuit Description
The electronic brake control module (EBCM) illuminates the electronic control unit (ECU) LED when the voltage supplied to the EBCM is less than 9 volts or when the EBCM detects an internal malfunction.
Conditions for Running the Diagnostic Fault
The ignition is ON.
Conditions for Setting the Diagnostic Fault
Either of the following conditions may cause the EBCM to illuminate the ECU LED.
| • | The voltage supplied to the EBCM drops below 9 volts rendering the EBCM inoperative. |
| • | The EBCM detects an internal malfunction. |
Action Taken When the Diagnostic Fault Sets
| • | The ABS indicator turns ON. |
| • | The ABS is disabled. |
| • | The EBCM illuminates the ECU LED. |
Conditions for Clearing the Diagnostic Fault
| • | Repair the condition responsible for illuminating the status lamps. |
| • | Perform the Status Lamps Reset Procedure. |
Diagnostic Aids
Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to the following:
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Air Antilock Brake System Schematics | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Does the red electronic control unit (ECU) LED remain illuminated? | Go to Step 3 | Go to Diagnostic Aids |
3 | Inspect for poor connections at the harness connectors of the electronic brake control module (EBCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 5 | Go to Step 4 |
4 | Replace the EBCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 5 | -- |
5 |
Does the red ECU LED remain illuminated? | Go to Step 2 | System OK |
