Wipers will not turn off!

boostdprobe91

Registered User
I recently got this 91 Super Coupe and ever since the ride home the wipers will not turn off. I've tried everything to get them to shut off but the just wont. Is there a certain relay that could have gone bad or something? or could the pulse board be bad in it.
 
I recently got this 91 Super Coupe and ever since the ride home the wipers will not turn off. I've tried everything to get them to shut off but the just wont. Is there a certain relay that could have gone bad or something? or could the pulse board be bad in it.

Could be the pulse board.

Can also be the wiper park switch (which is on the pulse board).

Before I REPLACED, I'd CLEAN CONTACTS.

And before I started with that, I'd snarf an EVTM (Electrical Vacuum Troubleshooting Manual) from eBay or Helm Inc. ( www.helminc.com ). While there, grab the Ford Factory Service Manual. The pair is $62.50 plus shipping nowadays new from Helm, when they have it in stock.

RwP
 
Could be the pulse board.

Can also be the wiper park switch (which is on the pulse board).

Before I REPLACED, I'd CLEAN CONTACTS.

Ralph, are you sure the 91 has the park switch in the module? I thought the 91 had the older style wiper motor, which had the park switch inside the motor. Just asking.
 
Ralph, are you sure the 91 has the park switch in the module? I thought the 91 had the older style wiper motor, which had the park switch inside the motor. Just asking.

I believe you're right Steve. There are circuits inside the wiper module to control the park function, but the actual switch is in the motor assembly.
 
I think it could be either(or wiring in between). The early motors are especially prone to water intrusion, which usually rusts the bearings/ case until it locks up, but I suppose that switch could go bad. The wiper interval control module( under the dash) Is more sensitive though, so I could see it being either.
 
I think it could be either(or wiring in between). The early motors are especially prone to water intrusion, which usually rusts the bearings/ case until it locks up, but I suppose that switch could go bad. The wiper interval control module( under the dash) Is more sensitive though, so I could see it being either.

I don't remember if the wiper module is involved with the Low and High speeds, or just with the delayed speeds. I can check my EVTM later. If you have the old-style motor, and the wipers work and stop, but fail to park, that is from a worn-out motor bearing. But in this case, it sounds like the park switch is never being activated, which suggests controls or wires are at fault.
 
I don't remember if the wiper module is involved with the Low and High speeds, or just with the delayed speeds.

The module is for delayed speeds only, but if I remember right, the low speed wiring routes through the module too- for the parking function.
 
So could it possibly be the switch inside the car? or could it be the motor?

The park switch is part of the motor itself. Or it's on the pulse board. Lemme check the EVTM for a 1991 ...

OK - it's not on the pulse board (which the 1991 EVTM doesn't show one!), for the Gen1's it's part of the wiper motor itself. Its function is to let the motors run until they're in park, so when it shorts, the unit will keep wiping.

The OTHER choice may be that the wiring is shorted around it.

There's a chance it's the interval governor, the module under the dash that powers the unit (if it's shorted, it won't see the switch open, so ... )

The signal is on the black/pink wire from the wiper motor.

Before you swap too many parts, I'd see if that line is grounded all the time or if it pops open when the unit is in the park area.

And if it pops open, but closes to ground when the blades go up very far, then it's not the motor. If it's grounded ALL the time, then it's the switch on the motor, and replacing with a later model (sealed) wiper motor may not be a bad idea.

RwP
 
Thanks guys for all the helpful information. I got them to stop working buy simply unhooking the battery and hooking it back up. it stopped them and they went into the park position. Thanks for everyones help. Now just need to get the windows fixed.
 
The park switch is part of the motor itself. Or it's on the pulse board. Lemme check the EVTM for a 1991 ...

OK - it's not on the pulse board (which the 1991 EVTM doesn't show one!), for the Gen1's it's part of the wiper motor itself. Its function is to let the motors run until they're in park, so when it shorts, the unit will keep wiping.

The OTHER choice may be that the wiring is shorted around it.

There's a chance it's the interval governor, the module under the dash that powers the unit (if it's shorted, it won't see the switch open, so ... )

The signal is on the black/pink wire from the wiper motor.

Before you swap too many parts, I'd see if that line is grounded all the time or if it pops open when the unit is in the park area.

And if it pops open, but closes to ground when the blades go up very far, then it's not the motor. If it's grounded ALL the time, then it's the switch on the motor, and replacing with a later model (sealed) wiper motor may not be a bad idea.

RwP

The interval governor serves the same function that a pulse board does on later cars. I think it has an array of capacitors of different ratings, one or more of which is selected at a given time, based on the position of the multi-function switch. The fill time for each capacitor varies. After it fills, it trips the relay, which simply applies power to the wiper motor. The rotation of the wiper motor shaft also rotates the electrical contacts within the motor, so the motor parks automatically when it completes one cycle. The old style motors have a simpler parking system than the later cars ... they don't move down out of sight, they just stop at the bottom of the windshield.

If I recall correctly from digging into an older wiper motor years ago, the most common problem is a worn-out bushing in one end of the motor, which lets the shaft move axially when the wipers are moving. That moves the electrical contacts and prevents the wipers from parking correctly.

Now, I am not 100% sure that the problem now is caused by that same thing. But testing should help figure it out. Another thing to look at it is pulling the upper cowl off (with the wipers shut off, obviously) and applying some force to the arm coming from the wiper motor. If it moves up and down, the motor bushing may be worn out.

I would not necessarily recommend swapping to the later motor. You have to chop off the old plug and rewire. I guess that's not a huge deal. But the older motor looks rebuildable to me.

If you do swap and plan to throw out the old motor, I would be interested in having the old one to tinker with.
 
Back
Top