Headlamp Switch: Testing and Inspection

WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS, REFER TO ELECTRICAL, RESTRAINTS BEFORE ATTEMPTING ANY STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE. FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY.

1. Disconnect and isolate the battery negative cable. Access and unplug the 9-way headlamp switch wire harness connector. Access and unplug the steering column wire harness connector.
2. Check for continuity between the driver door ajar switch sense circuit and key-in ignition switch sense circuit terminals of the headlamp switch. There should be continuity with the headlamp switch turned ON, and no continuity with the headlamp switch turned OFF. If OK, go to Step 3. If not OK, replace the faulty switch.
3. With the driver door closed, check for continuity between the driver door ajar switch sense circuit cavity of the 9-way headlamp switch wire harness connector and a good ground. There should be no continuity. If OK, go to Step 4. If not OK, repair the short circuit to the driver door ajar switch as required.
4. Check for continuity between the driver door ajar switch sense circuit cavities in the instrument panel half of the steering column wire harness connector and the 9-way headlamp switch wire harness connector. There should be continuity. If OK, go to Step 5. If not OK, repair the open circuit as required.
5. Access and unplug the buzzer module or the Central Timer Module (CTM) wire harness connectors. Check for continuity between the key-in ignition switch sense circuit cavity of the buzzer module or CTM wire harness connector and a good ground. There should be no continuity. If OK, go to Step 6. If not OK, repair the short circuit as required.
6. Check for continuity between the key-in ignition switch sense circuit cavities of the buzzer module or CTM wire harness connector and the 9-way headlamp switch wire harness connector. There should be continuity. If OK, (Refer to CHIME/BUZZER/CHIME/BUZZER MODULE - DIAGNOSIS AND TESTING). If not OK, repair the open circuit as required.