Grand Cherokee 2WD V8-4.7L VIN J (2004)
Blower Motor Switch: Testing and Inspection
BLOWER MOTOR SWITCH-MANUAL TEMPERATURE CONTROL SYSTEM
For circuit descriptions and diagrams, refer to the appropriate wiring information.
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 AN ACCIDENTAL
AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY.
1. Check for battery voltage at the 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 faulty fuse.
2. Turn the ignition switch to the OFF position. Disconnect and isolate the battery negative cable. Remove the a/c heater control from the instrument
panel. Check for continuity between the ground circuit cavity of the a/c heater control wire harness connector and a good ground. There should be
continuity If OK, go to Step 3. If not OK, repair the open circuit to ground as required.
3. With the a/c heater control wire harness connector unplugged, place the a/c heater mode control switch knob in any position except the OFF
position. Check for continuity between the ground circuit terminal and each of the blower motor driver circuit terminals of the a/c heater control as
you move the blower motor switch knob to each of the four speed positions. There should be continuity at each driver circuit terminal in only one
blower motor switch speed position. If OK, test and repair the blower driver circuits between the a/c heater control connector and the blower
motor resistor as required. If not OK, replace the faulty a/c heater control unit.
