Maintenance: Service and Repair

Fig. 113 Malfunction Indicator (CHECK) Light Reset:

In addition to displaying computer system malfunction codes (codes only on California models), the Malfunction Indicator (CHECK) Light on Federal trucks acts as an emission maintenance warning. The Malfunction Indicator (CHECK) Light warning light will come on at 60,000 miles for EGR and at 80,000 miles for Oxygen sensor.
To reset the warning light after servicing the indicated components, locate the Brown/White, Black and the green wires located under the left side of the dash (taped to the wiring harness above the relay box). At 60,000 mile intervals, unplug the Black wire connector from the Brown/White connector and plug it into the Green wire connector. At 80,000 mile intervals, return the Black wire connector to the Brown/White wire connector.