Introduction

The procedures contained in this information include all the specification, instructions, and graphics needed to diagnose Mark 20 Antilock Braking System (ABS) problems. The diagnostics in this information are based on the failure condition or symptom being present at the time of diagnosis.
When repairs are required, refer to the appropriate service information for the proper removal and repair procedure.
Please follow the recommendations below when choosing your diagnostic path.
1. First make sure the DRBIII is communicating with the CAB. If the DRBIII displays a "No Response" condition, you must diagnose that first.
2. Read DTCs (diagnostic trouble codes) with the DRBIII.
3. If no DTCs are present, identify the customer complaint.
4. Once the DTC or customer complaint is identified, locate the matching test in the Table of Contents and begin to diagnose the symptom.
An * placed before the symptom description indicated a customer complaint.
Diagnostic procedures change every year. New diagnostic systems may be added; carryover systems may be enhanced. READ THIS INFORMATION BEFORE TRYING TO DIAGNOSE A VEHICLE CODE. It is recommended that you review all information to become familiar with all new and changed diagnostic procedures.