Class 1 Serial Data Line

If all components are not accessible with a scan tool, check for an open in circuit 800 between DLC terminal "M" and S237. See WIRING DIAGRAMS .
If a single component is not accessible with a scan tool, check for an open in circuit 800 between S237 and the component. Check circuit 1807 for an open between DLC terminal No. 2 and the PCM. Check C100 for a bad connection. Repair wiring as necessary. If no fault is found, go to SYMPTOM INDEX table under SYSTEM TESTS.