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ErnieC

I checked the fuse and relay-- not the issue. I replaced the control arm switch -- not the issue. I took it to a shop. They check the motor-- not the issue. The shop says it might be the wiper control module. Where is this control module located and how do you test?

Rawze

My Prostar did that when it was brand new... only had 13 miles on it. Wipers were permanently on.. would not shut off.

On mine, it was the Cab controller fried.

may not be what is wrong with yours.. just sharing my own experience.

Truckdriven

(08-24-2022 )ErnieC Wrote: I checked the fuse and relay-- not the issue. I replaced the control arm switch -- not the issue. I took it to a shop. They check the motor-- not the issue. The shop says it might be the wiper control module. Where is this control module located and how do you test?

On My 2012 W900 (same cab) The wipers would go part way up then stop until you activated the switch again then they would go back to resting position, worked fine on high. There is a separate Relay for the High function and another for wash/lo/delay positions that was bad on my truck. To my knowledge your cab wiper system will be wired the same, that relay is labeled "Wiper on/off relay" on the fuse cover label, and the high relay is labeled "Wiper hi/lo relay". You say the relay was checked but I don't know how that was done, in my truck it is impossible to get access to probe relay terminals with the relay installed, I would simply replace those relays since they are so cheap and easy.

Also the high setting relay is activated directly from the control switch, no controller input, The lo/delay/wash settings signal goes to cab controller which then activates the relay so to Rawze' point it could still be the controller