Preliminary Diagnostic Information

When servicing the Antilock Brake System (ABS), the following steps should be followed in order. Failure to follow these steps may result in the loss of important diagnostic data and will lead to difficult and time-consuming diagnostic procedures.

1. Perform a vehicle preliminary diagnosis inspection. This should include:
^ Inspection of the master cylinder fluid reservoir for proper brake fluid level and signs of contamination.
^ Inspection of the Electro-Hydraulic Control Unit (EHCU) for any leaks or wiring damage.
^ Inspection of brake components at all four wheels. Verify no drag exists. Also, verify proper brake apply operation.
^ Inspection for worn or damaged wheel bearings.
^ Inspection of the wheel speed sensors and their wiring.
^ Verification of proper outer CV joint alignment and operation.
^ Verification that tires meet legal tread depth requirements.

2. Perform Diagnostic System Check. Initial Inspection and Diagnostic Overview
3. If any Diagnostic Trouble Codes (DTCs) are displayed, note the last malfunction that occurred. Diagnose and repair this malfunction first.
4. If no DTCs or mechanical component malfunctions are present, or if the malfunction is intermittent and not reproducible, test drive the vehicle while using the automatic snapshot feature of the scan tool. Perform normal acceleration, stopping, and turning maneuvers. If this does not reproduce the malfunction, perform an ABS stop, on a low coefficient surface such as gravel, from approximately 48-80 km/h (30-50 mph) while triggering the snapshot mode on any ABS DTC. If the malfunction is still not reproducible, use the enhanced diagnostic information to determine whether or not this malfunction should be diagnosed further based on frequency of the malfunction.
5. Once all system malfunctions have been corrected, clear the ABS DTCs.