Heated Mirror Switch: Testing and Inspection

The heated mirror switch, the solid state electronic heated mirror system control logic and timer circuitry the heated mirror system indicator lamp and the heated mirror relay are all integral to the a/c heater control. For circuit descriptions and diagrams.

1. Check the fused ignition switch output (run/start) fuse in the Junction Block (JB).
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 fused ignition switch output (run/start) fuse in the JB.
If OK, go to Step 3.
If not OK, repair the open circuit to the ignition switch as required.

3. Disconnect and isolate the battery negative cable. Disconnect the 3-way instrument panel wire harness connector for the heated mirror switch from the heated mirror switch connector receptacle on the back of the a/c heater control.
Check for continuity between the ground circuit cavity of the wire harness connector and a good ground. There should be continuity.
If OK, go to Step 4.
If not OK, repair the open ground circuit to ground as required.

4. Reconnect the battery negative cable. Turn the ignition switch to the ON position.
Check for battery voltage at the fused ignition switch output (run/start) circuit cavity of the 3-way instrument panel wire harness connector for the heated mirror switch.
If OK, go to Step 5.
If not OK, repair the open fused ignition switch output (run/start) circuit to the fuse in the JB as required.

5. Turn the ignition switch to the OFF position. Disconnect and isolate the battery negative cable. Reconnect the 3-way instrument panel wire harness connector for the heated mirror switch to the heated mirror switch connector receptacle on the back of the a/c heater control. Reconnect the battery negative cable. Turn the ignition switch to the ON position. Depress and release the heated mirror switch. The amber heated mirror system indicator lamp next to the heated mirror switch button should light.
If OK, go to Step 6.
If not OK, replace the faulty a/c heater control.

6. Back probe the fused heated mirror relay output circuit cavity of the 3-way instrument panel wire harness connector for the heated mirror switch on the back of the a/c heater control and check for voltage (battery voltage less the resistance in both outside mirror heating grids).
If OK, (Refer to HEATED MIRRORS/HEATED MIRROR GRID - DIAGNOSIS AND TESTING Heated Element).