The diagnostic system check is an organized method of identifying any problems caused by a malfunction in the ABS system. The service technician must begin diagnosis of any ABS complaint with the diagnostic system check. The diagnostic system check directs the service technician to the next logical step in diagnosing the complaint.

Use the following ordered procedure when servicing the ABS. Failure to use the following procedure may cause the loss of important diagnostic data and may lead to difficult and time-consuming diagnosis procedures.

1. Use the following procedure to perform a vehicle preliminary diagnosis inspection:

1.1.	Inspect the brake master cylinder fluid reservoir for contamination.

1.2.	Verify that the brake fluid level is correct.

1.3.	Inspect the brake components of all four wheels.

1.4.	Inspect for worn or damaged wheel bearings. Worn or damaged wheel bearings may cause a wheel to wobble.

1.5.	Inspect the wheel speed sensors and the wheel speed sensor wiring.

1.6.	Inspect the outer CV joint.

1.7.	Inspect the tires. Verify that the tires meet legal tread depth requirements.

1.8.	Diagnose and repair the DTC malfunction first.

2. Determine if the following conditions exist:

•	Not DTCs are present.

•	There are malfunctions in the mechanical components.

•	The failure is intermittent and cannot be reproduced.

3. If the above conditions exist, attempt to reproduce the malfunction:

•	Use the automatic snapshot feature of the scan tool while test driving the vehicle. Perform normal acceleration, stopping, and turning maneuvers during the test drive.

•	If the test drive does not reproduce the malfunction, perform an ABS stop on a low coefficient surface, such as gravel, from a speed of 48-80 km/h. (30-50 mph). Trigger the snapshot mode on any ABS DTC while performing the stop.

4. Clear the ABS DTCs after all of the system malfunctions have been corrected.

Diagnosing DTCs in the correct order is very important. Failure to diagnose DTCs in the specified order may result in the following: