Introduction

The procedures contained in this repair information include all the specifications, instructions, and graphics needed to diagnose Mark 20 Antilock Braking System (ABS) and Mark 20 Antilock Braking System with Traction Control. The diagnostics in these procedures are based on the failure condition or symptom being present at time of diagnosis.

Please follow the recommendations below when choosing your diagnostic path.
1. First make sure the DRB III is communicating with the CAB. If the DRB III displays a "No Response" condition, you must diagnose that first.
2. Read DTC's (diagnostic trouble codes) with the DRB III.
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.

All component location views are found under the named component.
All connector pinouts are found under the named component.
All schematics are are found under Diagrams

An * placed before the symptom description indicated a customer complaint.

When repairs are required, refer to the appropriate component for the proper removal and repair procedure.

Diagnostic procedures change every year. New diagnostic systems may be added; carry over systems may be enhanced. REVIEW THESE PROCEDURES BEFORE TRYING TO DIAGNOSE A VEHICLE CODE. It is recommended that you review the entire vehicle system to become familiar with all new and changed diagnostic procedures.