Grand Cherokee 4WD V8-4.7L VIN N (2000)
Rear Window Defogger Switch: Testing and Inspection
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS, REFER TO AIR BAGS AND SEAT BELTS/AIR BAGS BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE.
FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
1. Disconnect and isolate the battery negative cable. Remove the heater and air conditioner control unit from the instrument panel and disconnect the
11-way (manual temperature control) or 16-way (automatic zone control) instrument panel wire harness connector from the heater and air
conditioner control receptacle.
2. Check for continuity between the ground circuit cavity of the 11-way or 16-way instrument panel wire harness connector for the heater and air
conditioner control and a good ground. There should be continuity. If OK, go to Step 3. If not OK, repair the open ground circuit to ground as
required.
3. Connect two jumper wires to the heater and air conditioner control 11-way or 16-way connector receptacle. Connect one jumper from the ground
circuit terminal in the 11-way or 16-way heater and air conditioner control connector receptacle to a good ground. Connect the other jumper from
the fused rear window defogger relay output circuit terminal of the 11-way or 16-way connector receptacle to a 12-volt battery feed. The rear
window defogger switch LED indicator should light. If OK, go to Step 4. If not OK, replace the faulty heater and air conditioner control unit.
4. Check for continuity between the ground circuit and rear window defogger switch sense circuit terminals of the 11-way or 16-way heater and air
conditioner control connector receptacle. There should be momentary continuity as the rear window defogger switch push button is depressed, and
then no continuity. If OK, go to Step 5. If not OK, replace the faulty heater and air conditioner control unit.
5. Disconnect the 22-way instrument panel wire harness connector from the Body Control Module (BCM) connector receptacle. Check for continuity
between the rear window defogger switch sense circuit cavity of the 11-way or 16-way instrument panel wire harness connector for the heater and
air conditioner control and a good ground. There should be no continuity. If OK, go to Step 6. If not OK, repair the shorted rear window defogger
switch sense circuit as required.
6. Check for continuity between the rear window defogger switch sense circuit cavities of the 11-way or 16-way instrument panel wire harness
connector for the heater and air conditioner control and the 22-way instrument panel wire harness connector for the BCM. There should be
continuity. If OK, refer to Rear Window Defogger Relay in the Diagnosis and Testing. If not OK, repair the open rear window defogger switch
sense circuit as required.