* Fuse: Check the fuse box for a blown fuse that controls the rear window wiper and defroster. Replace the fuse if necessary.
* Switch: The switch that controls the rear window wiper and defroster may be faulty. Try wiggling the switch or turning it on and off several times to see if it works. If the switch is not working, you will need to replace it.
* Wiring: There may be a problem with the wiring that connects the switch to the rear window wiper and defroster. Check the wiring for any loose connections or damage. Repair or replace the wiring as necessary.
* Rear window wiper motor: The rear window wiper motor may be faulty. To test the motor, remove it from the vehicle and connect it directly to a power source. If the motor does not work, you will need to replace it.
* Defroster grid: The defroster grid may be damaged or disconnected. Check the defroster grid for any breaks or damage. Repair or replace the defroster grid as necessary.
If you are unable to diagnose and fix the problem yourself, you should take your vehicle to a qualified mechanic.
