Initial Inspection and Diagnostic Overview

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. check CKT 1807 for an open between DLC terminal "2" and the Powertrain Control Module (PCM). Also check C210 for a bad connection.
2. If a single component is not accessible with a scan tool, check for an open in CKT 800 between S237 and the component. If the wire is OK, refer to Engine Controls for Powertrain Control Module diagnosis, Antilock Brake System (ABS) for ABS diagnosis and to Air Bags and Seat Belts for Supplemental Inflatable Restraint (SIR) diagnosis.
Antilock Brakes / Traction Control Systems
Restraints and Safety 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 (see Troubleshooting Procedures). Diagnostic Aids
^ Refer to System Diagnosis.