Diagnosis And Testing - Automatic Dimming Mirrors: Notes

For complete circuit diagrams, refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin-out information and location views for the various wire harness connectors, splices and grounds.

1. Ensure that the automatic dimming mirror feature is NOT turned off.
2. Check the fused ignition switch output (run/start) fuse in the Power Distribution Center (PDC). If OK, go to step 2. If not OK, repair the shorted circuit or component as required and replace the ineffective fuse.
3. Turn the ignition switch to the ON position. Check for battery voltage at the fused ignition switch output (run/start) fuse in the PDC. If OK, go to step 3. If not OK, repair the open fused ignition switch output (run/start) circuit to the run-start relay in the PDC as required.
4. Disconnect the overhead wire harness connector from the automatic dimming inside rear view mirror. Check for battery voltage at the fused ignition switch output (run-start) circuit cavity of the overhead wire harness connector for the mirror. If OK, go to step 4. If not OK, repair the open fused ignition switch output (run/start) circuit to the fuse in the PDC as required.
5. Turn the ignition switch to the OFF position. Check for continuity between the ground circuit cavity of the overhead wire harness connector for the automatic dimming inside rear view mirror and a good ground. There should be continuity. If OK, go to step 5. If not OK, repair the open circuit to ground as required.
6. Place the transmission gear selector lever in the NEUTRAL position. Place the automatic dimming inside rear view mirror switch in the ON (green LED indicator illuminated) position. Cover the forward facing ambient photocell light 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 light sensor. The automatic dimming mirror glass should darken within 2 minutes if testing for the first time. For an immediate response, turn the mirror switch to the OFF position and back to the ON position with the forward-facing ambient light sensor still covered. This defeats the daylight detection logic of the mirror. If OK, go to step 8. If not OK, replace the ineffective mirror unit.
8. With the mirror darkened, place the transmission gear selector lever in the REVERSE position. The automatic dimming mirror glass should return to its normal reflectance. If not OK, replace the ineffective mirror unit.