1. Wiper Motor: While less likely if high speed works, a failing wiper motor could cause intermittent and low speeds to fail. The motor might have worn brushes or internal electrical problems that only manifest at lower power demands. Testing the motor directly (with a multimeter and carefully following wiring diagrams) is the best way to determine its condition. This often requires removal of the motor.
2. Wiper Switch: The switch itself might be faulty. Internal contacts could be worn or corroded, causing poor connection specifically on the lower speed circuits. Replacing the switch is the typical solution. This is often relatively easy, but location varies depending on the model.
3. Wiper Control Module (or Resistor Pack): Many vehicles, especially from this era, use a resistor pack or a dedicated control module to regulate the wiper motor speed. The resistor pack, often located near the wiper motor, is responsible for reducing voltage to create low and intermittent speeds. A failed resistor or short circuit within the module will prevent these speeds from working while high speed may still operate. This is a common failure point for intermittent wipers.
4. Wiring and Connections: Check all wiring connections related to the wiper system. Look for:
* Corrosion: Look for corrosion on connectors at the switch, motor, and resistor pack (if applicable). Clean these connections thoroughly with a wire brush and electrical contact cleaner.
* Broken Wires: Inspect the wiring harness for broken or frayed wires, particularly in areas that experience movement (like near the steering column or under the dash).
* Loose Connections: Ensure all connectors are securely plugged in.
5. Fuse: While less likely to cause only intermittent and low speed failure, check the fuse related to the wipers.
Troubleshooting Steps:
1. Check the fuse: This is the easiest first step.
2. Inspect wiring and connections: Look for corrosion, breaks, and loose connections. Clean or repair as needed.
3. Test the wiper motor (if comfortable): This requires some electrical knowledge and tools. You'll need to disconnect the motor and apply power directly to test its functionality. Consult a wiring diagram to avoid damage.
4. Check the resistor pack (if applicable): Locate the resistor pack and visually inspect it for damage. Testing this component usually requires a multimeter.
5. Test the wiper switch (if comfortable): This often requires more advanced tools and electrical knowledge, as you'll need to access the switch and test its circuits. If you are not comfortable with electrical work, this is best left to a professional.
If you're not comfortable working on your car's electrical system: Take it to a qualified mechanic. Diagnosing wiper issues can sometimes require specialized tools and knowledge. Improper electrical work can be dangerous and potentially damage other components.
