Headlamp Switch: Testing and Inspection

For complete circuit diagrams, refer to the appropriate wiring information.

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. Unplug the 9-way headlamp switch wire harness connector. 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 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 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.
4. Check for continuity between the driver door ajar switch sense circuit 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.
5. Unplug the buzzer module or the Central Timer Module (CTM) wire harness connectors. Check for continuity between the key-in ignition switch sense circuit 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.
6. Check for continuity between the key-in ignition switch sense circuit 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 ELECTRICAL/CHIME/BUZZER/CHIME/BUZZER MODULE - DIAGNOSIS AND TESTING). If not OK, repair the open circuit.