Automatic Day/Night Mirror

DIAGNOSIS AND TESTING - AUTOMATIC DAY / NIGHT MIRROR

For complete circuit diagrams, refer to Diagrams/Electrical.

1. Check the fuse in the Integrated Power Module (IPM). If OK, go to STEP 2. If not OK, repair the shorted circuit or component as required and replace the faulty fuse.
2. Turn the ignition switch to the ON position. Check for battery voltage at the fuse in the IPM. If OK, go to STEP 3. If not OK, repair the open circuit to the ignition switch as required.
3. Unplug the wire harness connector from the automatic day/night mirror. Check for battery voltage at the fused ignition switch output circuit cavity of the automatic day/night mirror wire harness connector. If OK, go to STEP 4. If not OK, repair the open circuit to the junction block as required.
4. Turn the ignition switch to the Off position. Check for continuity between the ground circuit cavity of the automatic day/night mirror wire harness connector and a good ground. There should be continuity. If OK, go to STEP 5. If not OK, repair the circuit to ground as required.
5. Turn the ignition switch to the On position. Set the parking brake. Place the transmission gear selector lever in the Reverse position. Check for battery voltage at the backup lamp switch output circuit cavity of the automatic day/night mirror wire harness connector. If voltage is present, reinstall the automatic day/night mirror wire harness connector and go to STEP 6. If not OK, repair the open circuit as required.
6. Place the transmission gear selector lever in the Neutral position. Place the automatic day/night mirror switch in the On (LED in the switch is lighted) position. Cover the forward facing ambient photocell sensor to keep out any ambient light.

NOTE: The ambient photocell sensor must be covered completely, so that no light reaches the sensor. Use a finger pressed tightly against the sensor, or cover the sensor completely with electrical tape.

7. Shine a light into the rearward facing headlamp photocell sensor. The automatic day/night mirror should darken. The automatic day/night mirror should darken within 2 minutes if testing for the first time. For immediate response, turn the vehicle OFF and back ON with the forward-facing light sensor still covered. This defeats the day-detect logic. If OK, go to STEP 8. If not OK, replace the faulty mirror unit.
8. With the mirror darkened, place the transmission gear selector lever in the Reverse position. The automatic day/night mirror should return to its normal reflectance. If not OK, replace the faulty mirror unit.