electrical issue somewhere , when unit is not running ( key activated) all headlamps on, front wiper works as required. when unit is running with all lights on front wiper will not work,but when lights are deactivated wiper works as required. tried grounding wiper motor to frame, no change, replaced control button panel, no change. there are no present codes.. any thoughts as to where i should look next, thanks
Unplug your lights one at a time to see if your wiper comes back on. Whichever light you unplug that enables your wiper to work replace that light assembly, not the bulb. One of the lights is drawing too much current which shuts down the valve power within the Vehicle Control Unit which shuts the wiper off.
Have 544k. Same issue. DTAC case says same thing. If yours is like mine, roof work lights on, wiper doesnt work, except if washer if activated. Replaced 3 corroded lamp assemblies. No joy. Tomorrow, I'll be replacing at least two with LED work lamps. Will return with answer later.
Thanks for this thread ……. just had a 744K with a wiper issue the same as posted above and it was a head scratcher. After finding this thread checked and the wipers would stop with the cab roof lights on …. so replaced the old incandescent cab roof lights with LED‘s and no wiper issues so far.