1. The Obvious:
* Fuse: Check your owner's manual to locate the fuse for the rear wiper motor. A blown fuse is the easiest fix. Replace it with one of the same amperage.
* Wiper Switch: Is the switch itself broken or stuck? Try wiggling it while attempting to activate the wiper.
* Blade: A worn, damaged, or improperly installed wiper blade can prevent proper operation. Try replacing the blade. Make sure it's securely attached.
* Frozen Mechanism: (Especially in colder climates) Ice can freeze the wiper arm to the glass or freeze the motor mechanism. Try de-icing the area.
2. More Involved Issues:
* Motor Failure: The rear wiper motor itself might have failed. This is a more significant problem requiring replacement.
* Wiring Issues: A break or short in the wiring harness leading to the motor could interrupt power. This requires tracing the wires to find the fault.
* Linkage Problem: The mechanical linkage connecting the motor to the wiper arm could be broken, disconnected, or seized. This usually involves inspection and possibly replacement of parts.
* Wiper Arm: The wiper arm itself may be broken or improperly connected.
* Electrical Connection: Check the electrical connector at the motor for corrosion or a loose connection. Clean or repair as needed.
* Relay Failure: Some vehicles use a relay to control the rear wiper. A faulty relay could prevent the wiper from functioning. This usually needs replacement.
* Ground Connection: A poor ground connection can prevent the motor from receiving sufficient power. Check for corrosion and secure ground wires.
* Wiper Motor Control Module: (Less likely, but possible) A dedicated control module for the wiper might be faulty. This typically requires diagnostics to confirm.
Troubleshooting Steps:
1. Start with the simplest: Check the fuse and the wiper blade first.
2. Visual Inspection: Carefully inspect the wiper arm, linkage, and motor for any obvious damage or obstructions.
3. Test the switch: Make sure the switch itself is functioning correctly.
4. Listen for the motor: When you activate the wiper, can you hear the motor trying to run? If not, it could be a power issue or a motor failure.
5. If you are uncomfortable working with car electronics, take it to a mechanic. Attempting electrical repairs without proper knowledge can be dangerous.
By systematically checking these possibilities, you should be able to narrow down the cause of the rear wiper malfunction. Remember to consult your owner's manual for specific information about your Expedition's wiper system.
