Rear Light Failure Sensor

If rear light failure warning light is not operating correctly, disconnect harness connector from rear light failure sensor located in trunk. Turn ignition on and ensure warning light glows. Start engine and ensure warning light goes out. If operation is not as specified, check bulb. If bulb is okay, go to next step.
Using a DVOM check for continuity between ground and terminals No. 1, 2, 6, 7, 11 and 12. See Fig 1. Continuity should exist on all terminals. Terminals No. 1, 2, 6, 7 and 12 will read slight resistance as they are grounded through bulbs. If continuity is as specified, go to next step. If continuity is not as specified, repair wiring.
Check for voltage between terminal No. 5 and ground. With headlights off, no voltage should exist. Turn headlights on. If battery voltage now exists, go to next step. If battery voltage does not now exist, check headlight switch and wiring.
Check for voltage between terminal No. 4 and ground. With engine off, no voltage should exist. Start engine. If battery voltage now exists, go to next step. If battery voltage does not exist, check wiring between instrument panel and rear light failure sensor.
Check for voltage between ground and terminals No. 9 and 10. With brake pedal released, no voltage should exist. Depress brake pedal. If battery voltage now exists, go to next step. If battery voltage does not exist, check brake switch and wiring.
Check for voltage between terminal No. 8 and ground. With ignition switch in LOCK or ACC position, no voltage should exist. Turn ignition on. If battery voltage does not exist, check ignition switch and wiring. If battery voltage now exists, test is complete. Substitute known good rear light failure sensor and recheck warning light operation.

Fig 1: Identifying Rear Light Failure Sensor Connector