1. Fuse: This is the simplest and most common cause. Check your owner's manual to locate the fuse for the rear wiper and use a test light or multimeter to verify its integrity. A blown fuse is easily replaced.
2. Wiper Motor: The motor itself could have failed. This requires more involved troubleshooting, possibly involving testing the motor's voltage with a multimeter while someone operates the wiper switch. A faulty motor needs replacement.
3. Wiper Switch: The switch in the interior might be faulty or have a broken connection. Testing continuity with a multimeter may be necessary. Again, replacement may be required.
4. Wiring and Connections: Look for broken, corroded, or loose wiring anywhere along the circuit from the switch to the motor. This includes connectors at the motor and any intermediary points. Corrosion is common near the rear hatch, particularly in areas exposed to water.
5. Linkage: The mechanical linkage connecting the motor to the wiper arm could be broken, dislodged, or seized. This would prevent the wiper arm from moving even if the motor is functioning. Inspection is required, and parts may need replacing or realignment.
6. Intermittent Wiper Problem: Sometimes the problem isn't a complete failure, but an intermittent one. This might point to a problem with a corroded connection, a loose wire that's making intermittent contact, or a failing motor.
7. Park Position: If the wiper is stuck in a parked position that's not aligned with the wiper rest position, this would indicate a mechanical linkage issue.
8. Relay: Some vehicles use relays to control the power to the wiper motor. A bad relay is another possibility. This would require checking the relay according to the vehicle's wiring diagram.
Recommendation: Start with the easiest and cheapest fixes (fuse check) before moving to more complex and potentially expensive repairs (motor or switch replacement). If you're not comfortable working on your car's electrical system, take it to a qualified mechanic for diagnosis and repair. A proper diagnostic scan using an OBD-II scanner may be helpful to pinpoint the issue, but the rear wiper system is often not fully covered by the scan.
