Diagnosis

1. Your diagnostic test procedure must begin with a thorough visual inspection of the ABS system components for damaged components or disconnected connectors.
A visual inspection consists of physically looking for the possible cause of a malfunction. A careful and thorough visual inspection of components may quickly identify the cause of a malfunction and eliminate the need for diagnostic testing.
PERFORM THE FOLLOWING VISUAL INSPECTIONS BEFORE DOING ANY DIAGNOSTIC TESTING. If a malfunction is not resolved by the visual inspection, proceed with diagnostic testing according to the instructions.
Brake Fluid Level Visually inspect the proper fluid level within the fluid reservoir.
Hydraulic Control Unit Visually inspect the hydraulic assemblies for leaks and for damaged or disconnected connectors.
Fuses Visually inspect that all fuses are properly installed
Wheel Speed Sensor Connectors Visually inspect both front wheel speed sensor connectors for damage or disconnection. Inspect the rear axle speed sensor connector.
Brake Fluid Lines Visually inspect brake fluid lines for any leaks or damage.
Wheel Speed Sensors Visually inspect all three wheel speed sensors and tone wheels for any damage.
Controller Antilock Brake (CAB) Visually inspect the CAB for a secure mounting and the CAB connector for damaged or loose connection.
Base Brake System Visually inspect the condition of the parking brake, rotors, drums, and calipers.

2. Connect the DRBIII(R) to the data link connector. First make sure that the DRBIII is communicating with the CAB. If the DRBIII(R) displays a "No Response" condition you must diagnose that first. For other DRBIII(R) related communication problems, refer to the Vehicle Communications test. Communications - Verbose Codes
3. With the DRBIII, read Kelsey-Hayes ABS active and stored diagnostic trouble codes and record them. If a wheel speed sensor code was present, perform the appropriate test. Using the DRBIII(R), either reset the module to erase all stored diagnostic trouble codes or use the erase command after reading all diagnostic trouble codes.
4. Turn ignition off, then on.
a. If the diagnostic trouble code doesn't come back, refer to the diagnostic trouble code description. If the DRBIII(R) displays diagnostic trouble codes, proceed to the appropriate diagnostic test(s) by locating the matching DTC test name in the table of contents.
b. If no diagnostic trouble codes are present at this time identify the customer complaint. Proceed to the appropriate test by locating the matching test in the table of contents and diagnose the symptom.
5. After repairing the customer complaint perform the System Verification Test.

WARNING: BEFORE PERFORMING ANY ROAD TEST, VERIFY THAT FULL BRAKING CAPABILITY IS PRESENT.