RAM 2500 Truck 4WD V10-8.0L VIN W HDC (2000)
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 heater and air conditioner control unit. Refer to Heater-A/C Control for heater and air conditioner control
removal and installation procedures.
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS, DISABLE THE AIRBAG SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE. DISCONNECT AND ISOLATE
THE BATTERY NEGATIVE (GROUND) CABLE, THEN WAIT TWO MINUTES FOR THE AIRBAG SYSTEM CAPACITOR TO
DISCHARGE BEFORE PERFORMING FURTHER DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE WAY TO DISABLE THE
AIRBAG SYSTEM. FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.
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 heater and air conditioner 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 fuse 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 heater and air conditioner 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 heater and air
conditioner control unit.
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 heater and air conditioner control and check for voltage (battery voltage less the resistance in both outside mirror heating grids).
If OK, refer to Outside Mirror Heating Grid diagnosis and testing procedures. If not OK, replace the faulty heater and air conditioner control unit.
