PRELIMINARY INSPECTION
Verify customer complaint by operating suspected system. Visually inspect for obvious signs of mechanical and electrical damage. Inspect for blown fuses and damaged relays. Inspect for loose or corroded connections, damaged wiring harnesses and/or switches. Check for a broken or partially broken wire inside insulation, which could cause system malfunction but prove good in a continuity/voltage check with system disconnected. Ensure any aftermarket electronic equipment is properly installed. If fault is found, repair as necessary. If no fault is found, diagnose by symptom. See SYMPTOM INDEX table under SYSTEM TESTS.
Diagnostic Procedure
- Test the battery positive voltage circuit of the DLC for an open or a short to ground. If there is no fault, go to next step. If there is any fault, repair and recheck system operation.
- Test the ground circuit at DLC terminal No. 4 for an open. If there is no fault, go to next step. If there is any fault, repair and recheck system operation.
- Inspect for poor connections at DLC terminals No. 4 and 16. If there is no fault, go to next step. If there is any fault, repair and recheck system operation.
- The scan tool may be malfunctioning. Refer to the scan tool user guide.
TEST B: SCAN TOOL WILL NOT COMMUNICATE WITH COMPONENTS
For testing procedure, refer to flowchart. (Scheme 1)and (Scheme 2).
