Wipers won't stay down

[Gray87GMC]

I just picked up an 87 GMC for a steal, only thing wrong with it was the wipers parked in the middle of the windshield.

I think no problem and buy it. I search online and see that sometimes a switch goes bad on the wiper motor, so I replace the motor.

Doesn't fix the problem so I go looking for the wiper module under the steering colum and it doesn't have one, the wires are just plugged into each other.

So I spent 100 bucks on a new one and put it in. Same problem... someone help please. What is left to fix?!?

 

[Gray87GMC]

I should add that the wipers stroke perfectly, they just park in the middle when I turn off the switch... so it can't be a linkage issue.

 

[RustyPile]

I'm trying to figure out how a failed window motor switch has anything to do with the wipers??????

When you move the wiper switch to "OFF", do the wipers stop immediately or do they continue to run a partial stroke and "park" in the same place each time?? If they stop immediately, the park switch on the wiper motor is bad.. If they continue on a partial stroke, several things could be the cause.. Wrong wiper motor, wrong park switch, wrong or incorrectly installed linkage, among others...

[EDIT] Ok, I see you edited your post about 20 minutes after I posted.. So you replaced the wiper motor.. If your replacement was just the basic motor, you had to transfer the BAD park switch among other items, to the replacement motor... That's why you still have the same symptoms..

 

[Gray87GMC]

I'm trying to figure out how a failed window motor switch has anything to do with the wipers??????

When you move the wiper switch to "OFF", do the wipers stop immediately or do they continue to run a partial stroke and "park" in the same place each time?? If they stop immediately, the park switch on the wiper motor is bad.. If they continue on a partial stroke, several things could be the cause.. Wrong wiper motor, wrong park switch, wrong or incorrectly installed linkage, among others...

I meant wiper motor. I replaced the wiper motor. When I turn off the switch on the column, the wiper continue to finish their stroke and then park back in the middle.

 

[RustyPile]

Looks like we're playing post tag.. I've always thought this should be an Olympic event..

Back to the subject at hand.. You didn't say if you had to transfer some parts over to the replacement motor.. I suspect you did.. If this is the case, you probably have an incorrect park switch on the motor..

 

[Gray87GMC]

Sorry, wasn't trying to confuse, just clarify. Hmm, the park switch is separate from the motor? I just bought a new motor, loosened the three screws that hold it on and separated from linkage, and put the new one on. Thanks for for the help! The motor looked like all one piece to me??

 

[RustyPile]

Here's a brief explanation of how the electrical circuit works on the wipers.. 12 volts is fed to the wiper motor from the ignition switch.. The wiper switch provides the ground path.. The park switch also provides a ground path that is actuated by a cam attached to the wiper mechanism on the motor.. When you turn the wipers off, the park switch maintains a ground path until the wipers reach a certain position determined by that cam.. The cam opens the switch and the wipers stop... The park switch knows the position of the wiper blades as they travel across the windshield -- the motor doesn't. Therefore the park switch must be properly "clocked" to the motor in order for the blades to "park" in the correct position...

 

[Gray87GMC]

So where can I find the park switch in relation to the wiper motor? I'm not seeing anything around it.

 

[RustyPile]

Austin, I was an automobile mechanic in the "heyday" of these old trucks. I've been retired for many years and some of this stuff kinda foggy in my mind.. Some of the wiper motors are "sealed" into one non-serviceable unit.. The park switch is not on the outside in the open. If there are no screws holding the washer pump to the motor gear case, then the park switch is not serviceable either.

You mentioned a wiper module under the dash and noted the wires are plugged into each other??? I'm assuming your truck came equipped with delay wipers and you were looking for the delay module.. I've never experimented with removing a delay module and leaving all other delay related components in place.. It's possible that the missing delay module is causing your problem.. It could be that because the delay switch is not "seeing" the module, it is causing some funny things to happen as the wipers are trying to park. When eliminating a component of a multi-part system, some "work around" steps must be taken other than just plugging random wires together..

During my working days, I never eliminated a component.. I either repaired the faulty component or replaced it.. Some people do work like that and that's why so many old vehicles have so many hacked up repair jobs committed on them... Maybe someone on here can shed some additional light on your situation..

 

[RustyPile]

So where can I find the park switch in relation to the wiper motor? I'm not seeing anything around it.

With delay wipers, there are 2 park positions.. One is the pause position between wiper pulses where the wipers just pause near the bottom of the windshield. The other position is where they park when turned off totally.

Here is a picture of the delay relay and washer pump assembly removed from the motor. The black cover at the top of the picture covers everything except the washer hose bibs. The park switch is part of this assembly and is located under the metal frame. If yours looks like this one everything is serviceable separate from the wiper motor..

You must be registered for see images attach

 

[ajd89]

For a minute there I thought you were the one that just bought my old 87 it was grey and I thought I sold it for a steal. but that was in mi. LOL but I had the same problem with the wipers they would never shut off. I had to take the wiper switch and turn it counteclockwise like past the off to stop the wipers. you had to stop them when they were down or it would stop in the middle of the window though not sure how else to explain it.

 

[Gray87GMC]

With delay wipers, there are 2 park positions.. One is the pause position between wiper pulses where the wipers just pause near the bottom of the windshield. The other position is where they park when turned off totally.

Here is a picture of the delay relay and washer pump assembly removed from the motor. The black cover at the top of the picture covers everything except the washer hose bibs. The park switch is part of this assembly and is located under the metal frame. If yours looks like this one everything is serviceable separate from the wiper motor..

You must be registered for see images attach

Hmm, in mine the motor and the washer pump are two totally separate pieces. I see what you're saying about the two park positions. Thank you for all your help. Back to taking things apart and seeing what I can figure out!

 

[Gray87GMC]

For a minute there I thought you were the one that just bought my old 87 it was grey and I thought I sold it for a steal. but that was in mi. LOL but I had the same problem with the wipers they would never shut off. I had to take the wiper switch and turn it counteclockwise like past the off to stop the wipers. you had to stop them when they were down or it would stop in the middle of the window though not sure how else to explain it.

At least yours would stop when they were down if you turned the switch in the right place. If I turn my switch off when they are in the down position, as soon as I turn the truck back on they go right back to the middle

 

[Honky Kong jr]

If they don't go down in 4 hours call your doctor...

 

[RustyPile]

.....<snip>..... If I turn my switch off when they are in the down position, as soon as I turn the truck back on they go right back to the middle

That leads me to believe the problem is in the delay circuitry, not the park circuitry... If your wiper motor has the washer pump and delay circuitry like the picture I posted earlier, then there is no "module" under the dash.. Everything is on the turn signal "stalk" on the column and the wiper motor on the firewall, with only wiring between the two..

I believe I can help you get to the heart of the problem.. I have a collection of old shop manuals out in the shop.. For the time being, just don't do anything more with your wipers.. Give me the weekend to dig through my "library" and see what I can find specific to your problem..