* Faulty wiper switch: The most common cause. The switch itself might be internally shorted or jammed, constantly sending power to the wiper motor.
* Worn or damaged wiper switch connector: The wiring harness connecting to the switch can become corroded, damaged, or have loose connections. This can lead to intermittent or constant operation.
* Problem with the wiper motor: While less likely to cause *constant* operation, a faulty wiper motor could be stuck in the "on" position. This is more likely to manifest as erratic operation or slow speeds than continuous running at full speed.
* Short in the wiring: A short circuit anywhere in the wiring harness leading to the wiper motor will send power continuously. This could be caused by damaged insulation rubbing against metal, or water intrusion.
* Faulty wiper control module (if equipped): Some vehicles, especially later models, use a control module to manage various functions including the wipers. If this module is defective, it might malfunction and keep the wipers running. (Less likely in a '92 Econoline, but possible.)
* Stuck relay: The wiper system uses a relay to switch the high current needed for the motor. If the relay is stuck closed, the wipers will stay on.
* Body control module (BCM) issue (if equipped): Similar to a dedicated wiper control module, a BCM can control various functions, including wipers, and a fault could cause them to run continuously. Again, less likely on a '92 but possible depending on specific trim level.
Troubleshooting Steps (in order of easiest to hardest):
1. Check the switch: Try wiggling the wiper switch stalk. If the wipers change speed or stop momentarily, it's highly likely a faulty switch.
2. Inspect the wiring: Look closely at the wiring harness going to and from the wiper switch and motor for any visible damage, corrosion, or loose connections. Pay close attention to areas prone to water damage.
3. Check the relay: If you can locate the wiper relay (consult a wiring diagram), try swapping it with a known good relay of the same type.
4. Test the wiper motor: This is best done with a wiring diagram and a multimeter, to ensure power is not constantly supplied to the motor itself, irrespective of the switch or relay.
If you are not comfortable working with car electrical systems, it is best to take the van to a qualified mechanic for diagnosis and repair. Attempting repairs without proper knowledge could lead to further damage or injury.
