Initial Inspection and Diagnostic Overview

ECM DATA LINE
1. If all components are not accessible with a scan tool, check for an open in CKT 461 between DLC terminal "M" and S215.
2. If a single component is not accessible with a scan tool, check for an open in CKT 461 between S215 and the component. If the wire is OK, refer to:
^ Computers and Control System for Computer diagnosis. Computers and Control Systems
^ Brakes for ABS diagnosis. Antilock Brakes / Traction Control Systems
^ Heating and Air Conditioning for Heater and A/C Control Assembly diagnosis. Heating and Air Conditioning

^ Check for a broken (or partially broken) wire inside of the insulation which could cause system malfunction but prove "GOOD" in a continuity/voltage check with a system disconnected. These circuits may be intermittent or resistive when loaded, and if possible, should be checked by monitoring for a voltage drop with the system operational (under load).
^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of other systems (Refer to General Troubleshooting Procedures). Diagnostic Aids