For 1990-2009 cars

### Circuit Description

The ABS Diagnostic System Check is an organized approach to identifying problems associated with the ABS. This must be the starting point for any ABS related concern and will direct you to the next logical step in diagnosing a malfunction. Most system malfunctions are linked to faulty wiring, connections and occasionally, to components. Understanding the ABS system and using the diagnostic tables correctly will reduce diagnostic time and prevent unnecessary parts replacement.

### Test Description

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

1. A flashing or inoperative green VLT LED indicates a fault in the ignition 3 voltage or ground circuits to the EBCM. During normal operation, the green VLT LED is always illuminated when the ignition is ON.

2. An illuminated ECU LED indicates a fault in the ignition 3 voltage or ground circuits to the EBCM or an EBCM internal malfunction. This fault must be repaired prior to proceeding with any other fault diagnosis.

3. The EBCM does not display faults that are not current.

Step | Action | Yes | No
--- | --- | --- | ---
1 |

1. Turn ON the ignition.
2. Observe the LEDs on the EBCM after the ignition has been ON for 10 seconds.

Is the green VLT LED ON steady?

Go to Step 2

Go to Green VLT Status Lamp Inoperative

2 | Does the EBCM display an illuminated red ECU LED? | Go to Status Lamps Illuminated - Engine Control Unit | Go to Step 3
3 | Does the EBCM display any other illuminated red LEDs? | Go to Status Lamps Reference Table | Go to Symptoms - Air Antilock Brake System