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 and using the diagnostic tables correctly will reduce diagnostic time and prevent unnecessary parts replacement.

### Test Description

The number below refers to the step number on the diagnostic table.

1. Lack of communication may be due to a malfunction of the UART serial data circuit. The specified procedure will determine the particular condition.

Step | Action | Yes | No
--- | --- | --- | ---
1 | Install a scan tool. Does the scan tool power up? | Go to Step 2 | Go to Scan Tool Does Not Power Up in Data Link Communications
2 |

1. Turn ON the ignition.
2. Attempt to establish communication with the Hydraulic 4WAL 4 Sensor (EBCM).

Does the scan tool communicate with the EBCM?

Go to Step 3

Go to Scan Tool Does Not Communicate with Electronic Brake Control Module in Data Link Communications

3 | Select the Hydraulic 4WAL 4 Sensor Display DTCs function on the scan tool. Does the scan tool display any DTCs? | Go to Diagnostic Trouble Code (DTC) List | Go to Symptoms - Antilock Brake System