Window wiper issue. What creates the interval?
 

I have a wiper issue in my '71 911. They work, but in the interval mode, the interval cycle seems too short. The wiper does not make a full wipe, but stops somewhere in the middle of the window on the back run.

I have checked the wiring diagram but I can't find a relay which operates this interval. I only find the steering wheel switch and the wiper motor. Can anyone tell me what creates that interval cycle? Any other ideas as to why the interval cycle is cut short?

Thanks for your help!

Maybe this will help you

http://www.techlib.com/files/wiperkik.pdf

There is some on that subject in the archives, use search to look. Here is one thread that might help:

http://forums.pelicanparts.com/porsche-911-technical-forum/363219-crazy-windshield-wipers.html

I have checked the wiring as per the Crazy wipers post, but all seems in order. There is another red wire on one pole which I will need to track to see where that ends.

Thanks sofar!

Does it stop even with the interval set to its lowest setting? Maybe a bad / dirty potentiometer? Sometimes our old electrical systems need a good cleaning.

I have no experience with 1971, all I can do is reference my '88. Aside from the wiper stalk on your steering column, do you have a small round switch above your speedometer? My '88 has one, and this actuates the intermittent wiper.

If you have one, chances are that it's probably just dirty. Spray it with electrical contact cleaner and work it back and forth.

If you don't have one, the problem is probably in your wiper stalk. You can clean it up, or replace it.

My intermittent wiper was acting funky. I replaced the stalk, and they now work perfectly. Yeah, I spent the $120 bucks...I won't be worrying about going back in their in another week, another several months or another few years...it's done.

The wipers on my '87 act crazy as well. I cleaned up the switch when replacing the steering bushing and thought they were working fine. Last week in some rain I was using the intermittent for about 10 minutes or so and then they started speeding up and finally they would not park at all. I had to time the off switch to when they were near park to turn them off. This is a real nuisance. Any suggestions? Is it the intermittent rotary switch going bad?

I have a 1975 911s, and this is how the wipers work:

The wiper switch consists of terminals # 53a, 53, 53b, 53i, 53e, and 53c. During wiper park cycle, 53e (blue wire) is connected to 53a (red wire, +12 v all the time). The connection is made when the wiper switch is off and the motor is not in the park position. The motor makes connection between 53e and 53a with an internal disk. The wiper switch connection between 53e and 53 puts the wipers into the slow mode, until the disk inside the motor turns to the park or off position.

53a Red = +12 v all the time
53 Red/Black (violet?) = slow speed wipers
53b black/yellow = medium speed wipers
53i green = fast speed wipers
53e blue = park at slow speed
53c black = washer pump motor

If you are having trouble with the park cycle, I'd check that the internal disk is clean.

So that means disasembling the wiper motor to check and clean the disk?

Ok, I found out that the '70/'71 models had 2 more components in the total wiper circuit. These are a 1) Wiper Interval switch and 2) Wiper Follow Up switch. I have seen the correct wiring diagram with these included, but does anyone know what these switches do?

It seems that if the wiper stalk is set at "interval", a current passes through switch 1 to switch 2 and then to the motor. What does which switch? Which can be responsible for a short interval and no auto return to the home position?

Thanks again!

My 79 would not park the wipers and the intermittant would not work until i took the stalk switch out and bent / cleaned the contact that the stalk arm controls. No more problems. Pretty easy to do. I would look at that first, especially if they wont park.

Well I thought I would keep this thread alive with more 71' Wiper issues.

Mine however seems a bit different than described. I have verified the wiring is indeed correct now, it was wrong. I have the capacitor inline as original and everything seems as it should be.

The issue is that all wiper speeds are very slow. The first speed actually will jam, second barely moves the wipers if they are off the window and third is basically barely what I would call a normal speed but again slow.

The motor works fine and will go full speed if hot wired. Anybody seen this??

Inside the wiper housing is a cage of rodents. When you pull the wiper switch, an electrical shock is delivered to the rodents, causing them to run and spin a wheel under their feet. When the wipers complete their cycle, another switch is triggered, delivering another shock.

The innovation behind interval delay wipers was to give the rodent a supply of cheap alcohol to drink. The amt. they get determines the delay in the interval cycle.

If the rodents get tired, or have a bad hangover, then the wipers will be balky and slow. The comment is often made that the "motor is tired."

Dude...you really have to lay off the sauce a bit! ;)