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-   -   CRAZY windshield wiper problem!! (http://forums.pelicanparts.com/porsche-911-technical-forum/533420-crazy-windshield-wiper-problem.html)

uwanna 03-27-2010 06:41 AM

CRAZY windshield wiper problem!!
 
Crazy wiper problem on my "80SC just started happening! Sometimes when I blow the horn, the wipers swipe once. Also when I turn on the headlights, the wipers turn on, and I CAN'T turn them off. Also sometimes when I use the turn signals, they come on.
The wipers operate normaly under all other conditions, including intermittant operation.
I took off the wheel/etc and checked out the wiper switch. Everything AOK. So I took out a couple of gauges to get to the wiper motor, and pulled off the blk/violet wire that is used for low speed wiper operation. The crazy things stopped, and of course have no low speed wipers, but other speeds work OK, but now the wipers won't "park"and intermittant no longer works. They just stop where they were when you turned them off. Have looked at the Bentley wiper wiring diagram, and have figured out how the "park" function works (using the Int Relay circuit to the blk/violet wire)
Now looking at the wiring diagram, it appears the only way the wipers can come with the wiper switch off is thru the Int Relay. My deduction is it seems when I turn on the headlights, honk horn, or sometimes use turn signals, the Int Relay is "energizing" by it self! Perhaps the internal transistor that switches the Int Relay on is weak or marginal, and a spike or dip in voltage causes the relay to energize.
Anyway, I am not looking foward to pulling all the fresh air blower stuff, just to get to the Int Relay and replace it, plus it's not a cheap relay!
Well there is my dilema, and I am just wondering if anyone has had a similar sympton, and I solicate your thoughts on my diagnosis.
Thanks for any help,
Grant

uwanna 03-27-2010 04:17 PM

any ideas?

pete3799 03-27-2010 05:40 PM

An exorcism?
Honestly don't know. My int. switch has stopped working and the steering wheel swich has started doing the stop where they are routine but haven't looked at them yet.

uwanna 03-27-2010 06:11 PM

pete3799,
Your problem would be a classic symptom of a bad intemittant relay. If the int relay is not able to energize through the dashboard switch/reostat, the int function won't work.

As far as parking the wipers, what happens is, during normal wipeing there is a "contact and a metal disk" in the motor that provide a circuit to the int relay when the motor is turning. When you turn off the wipers switch, the circuit is completed to the int relay, energizing it. This provides power to the motor thru the contacts in the int relay, till the "contact and metal disk" turn to a blank space on the disk, removing power to the motor. Then everything stops, Voila! parked wipers.
I don't think you dash int switch/reostat is bad, because even if it was, the park function would still work.

Sounds like you'll be buying a relay and pulling your fresh air blower too!
Could PAG have thought of a more inaccessable place to place that damned int relay!!!

pete3799 03-27-2010 06:55 PM

That sounds like the fix.
I'm going to check my steering wheel switch first as i think i read on here somewhere that it
can also cause the same problem.
Just got done doing spring plate bushings and need to get my ride height dialed in before i tackle the wipers.

uwanna 03-27-2010 08:00 PM

Just looked at the Bentley wiper diagram. It is possible that the wiper switch could cause the "no park" problem. To check if the switch is the problem, you need to check if you have continuity between the "blue" wire on the switch and the "blk/violet" wire, with the wiper switch in the off position. If you have continuity, the switch is good.
if the switch reads AOK, I'm afraid you have a relay problem!

pete3799 03-27-2010 08:06 PM

I'll check that out. thanks.


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