* Worn-out wiper motor: While less common to affect only one wiper, a failing motor could be experiencing internal issues affecting only one of the wiper arms' linkages.
* Faulty wiper motor linkage: This is a very likely culprit. The linkage connecting the motor to the wiper arms is mechanical and can rust, break, or become dislodged. A problem in this linkage will typically only affect one arm.
* Broken or disconnected wiper arm: Check the arm itself for any damage or looseness. It might be detached from the linkage or broken.
* Wiring issue: A broken or corroded wire supplying power to *only* one wiper motor is possible, though less probable than mechanical issues. Check the wiring harness near the motor for damage.
* Fuse: While less likely to affect only one wiper, a partially blown fuse could provide enough power for one wiper but not the other. Check the fuse box for the wiper motor circuit.
* Wiper switch: A faulty switch might be sending power intermittently or only to one wiper. This is less likely, as a totally failed switch usually disables both wipers.
Troubleshooting Steps:
1. Visual Inspection: Start with a careful visual inspection of the linkage, wiper arms, and wiring. Look for anything obvious like broken parts, corrosion, or loose connections.
2. Check the Fuse: Locate the wiper motor fuse in the fuse box (usually under the hood or dashboard) and verify it's intact.
3. Test the Wiper Motor (Advanced): If you're comfortable with basic automotive electrical work, you could try testing the motor's power directly using a multimeter. This is more involved and requires some electrical knowledge.
4. Check the Wiper Switch (Advanced): Testing the wiper switch involves using a multimeter to check the circuit's continuity and verify it's sending power to both wipers as expected. This requires more advanced electrical diagnostics.
It's likely a mechanical issue with the linkage, but a systematic approach, starting with the simplest checks, will help you pinpoint the problem. If you're not comfortable working on your car's electrical system, it's best to take it to a mechanic for diagnosis and repair.
