Problems with the intermittent wiper function usually stem from one of these areas:
* Body Control Module (BCM): This is the most likely culprit. A faulty BCM can cause intermittent wiper problems, among many other electrical issues. Replacing the BCM requires a dealer or specialized shop to reprogram it to match your vehicle's configuration. This is an involved and potentially expensive repair.
* Wiper Motor: A failing wiper motor can also lead to inconsistent or non-functional intermittent speeds.
* Wiring harness: Damaged or corroded wiring between the BCM, the wiper switch stalk, and the motor can disrupt the signal. This requires tracing the wiring for breaks or corrosion.
* Wiper Switch Stalk: While less common, a faulty wiper switch could be interfering with the signal for the intermittent function. This is relatively easy to replace, though the intermittent function might still not work if the problem lies elsewhere.
To diagnose:
1. Check the fuses: Make sure the appropriate fuses for the wipers are not blown.
2. Test the wiper switch: See if the other wiper speeds work correctly (high, low). If none work, the problem is likely in the switch or the wiring between the switch and the motor.
3. Have the BCM scanned: A professional mechanic can use a scan tool to read diagnostic trouble codes (DTCs) from the BCM. This will often pinpoint the source of the electrical problem.
In short, there's no simple relay to swap out. Diagnosing the intermittent wiper issue requires a systematic approach, potentially involving professional help, especially if the BCM is suspected.
