* Multi-function switch (wiper switch): This is the most common culprit. The switch itself can fail internally, causing the wipers to stick in the "on" position or malfunction. A faulty connection within the switch is also possible.
* Wiper motor: While less likely to be the sole cause of wipers *never* turning off (they'd likely just run erratically or not at all), a malfunctioning wiper motor could contribute to the problem if it's not receiving the correct signals to stop.
* Wiring harness: Damaged, corroded, or shorted wires in the wiring harness leading to the wiper motor or switch can prevent the proper signal from reaching the motor, or cause it to receive a constant "on" signal. Check for broken or frayed wires, particularly near the steering column and under the hood.
* Wiper motor relay: The relay acts as a switch for the wiper motor, controlled by the multi-function switch. A stuck relay could constantly supply power to the motor.
* Grounding issue: A poor ground connection can interfere with the electrical system's ability to properly control the wipers.
* Park switch: Some wiper systems use a park switch to ensure the wipers stop in the "park" position. A faulty park switch could prevent the wipers from turning off. (Less common on older vehicles.)
* Body Control Module (BCM) (less likely): While less common in this older vehicle, a malfunctioning BCM could theoretically cause this issue, though other symptoms would likely also be present.
Troubleshooting Steps:
1. Start with the simplest: Check the fuse for the wipers. A blown fuse might seem counterintuitive, but it's possible a short is causing the fuse to blow repeatedly and causing the system to malfunction.
2. Inspect the multi-function switch: This is the most likely culprit. Try wiggling the switch to see if it affects the wipers. If it's visibly damaged or the connections look corroded, replacement is probably needed.
3. Check the wiring harness: Visually inspect the wiring leading to the wiper motor and switch for any damage or corrosion.
4. Test the wiper motor relay (if equipped): This requires locating the relay and testing its function with a multimeter or by swapping it with a known-good relay (if possible).
5. Check the grounds: Look for and clean any ground connections related to the wiper system.
6. If all else fails: Take it to a mechanic. Diagnosing electrical issues can be challenging, and a professional with diagnostic tools can quickly pinpoint the exact problem.
Remember safety first! Disconnect the battery negative terminal before working on any electrical components.
