Initial Inspection and Diagnostic Overview

PCM DATA LINE
1. If all components are not accessible with a scan tool, check for an open in CKT 800 between Data Link Connector (DLC) terminal "9" and S237.
2. If a single component is not accessible with a scan tool, check for an open in CKT 800 between S237 and the component. Check the Class 2 Serial Data Line between the Data Link Connector terminal "2" and the Powertrain Control Module (PCM). Also check C100 for a poor connection. If the wires are OK, refer to Antilock Brake System for ABS diagnosis and to Air Bags (Supplemental Restraint Systems) for Supplemental Air Restraint diagnosis.
Antilock Brakes / Traction Control Systems
Air Bag Systems
^ 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
^ Refer to System Diagnosis. System Diagnosis