Wipers wont turn off

[BennSport]

Has anyone faced an issue with the wipers on an early 944 not turning off no matter what position they’re put in? I would like to see if this is repairable, as a new wiper switch assembly costs $600. I have seen some information regarding using vanagon switches, but from what I gathered it’s not fully plug and play. I will end up ordering some as a last resort, but I wanted to test the waters here first. If anyone has any more information regarding this please let me know, thanks in advance.

[gb951]

If originality is not an issue for you, you could always wire in a separate on/off switch on the main power feed to the motor.

[Spokayman]

I’m not sure if it’s the same wiper system electronics, but I encountered the same problem on a ‘95 Carrera and it turned out to be a defective relay.
I looked up which relay controls the wipers, unplugged it, and plugged a spare back in. No more problem.

[944er]

Have you pulled your intermittent wiper relay to make sure it is not the problem?

[BennSport]

I have not pulled my relay yet, I didn’t even think to check that. Is there a way to bench test it?

[944er]

Well, if you pull it and your wipers stop, I think it is bad.

[dr bob]

In my experience with similar cars, the possible causes are a sticking switch (you can test for that electrically with motor and switch unplugged...), a sticking relay (you can test for that electrically with the motor unplugged...) or a problem with the 'parking' contact in the wiper assembly, where the motor never gets to the 'park' gap in a rotary contact. Yes, you can diagnose that electrically, but this one is easier with the motor plugged in. Remove the wipers arms so you don't scratch the glass, and connect a battery maintainer while you fiddle.

I don't have the wiring diagrams for your car or I could write a test protocol if there isn't one already.

[BennSport]

I’ll pull the relay sometime this week, and see what happens to the wipers when I do. So if I pull the relay and the wipers turn off that tells me that the relay needs to be fixed?

[dr bob]

I’ll pull the relay sometime this week, and see what happens to the wipers when I do. So if I pull the relay and the wipers turn off that tells me that the relay needs to be fixed?

Not directly. Try unplugging the switch first, with wiper motor running and wiper arms removed.

Then try removing the fuse with them running, switch plugged back in, arms still removed. The motor will stop. If putting the fuse back in causes more than motor moving to arms-sparked position, suspect the relay.

Inside the motor and gearbox assembly there's a wiper-style switch that gets power from X or 15, same as the motor normally does via fuse but not the column stalk switch or relay. The arm that wipes across the arc of the switch contact area, and supplies power to the motor until it gets to a gap in that arc-shaped section that corresponds to wiper-parked.

I'm a bit blind without the CFD's for your car, so can't give you wire colors or connector pins to test or disconnect. But some careful testing and disconnecting of the connector pins at the motor will tell you a lot about how power is applied to it to keep it running.

I will suggest that the relay is probably where I'd focus initial attention testing. The easiest test is to just plug in a known-good relay. Many 80's Porsches have been 'upgraded' with compatible relays from period Volkswagen cars to get fancier delay functions, like delay 'learning' from stalk pulls. I you have one of those and still have the original relay, by all means plug the functional original relay back in for testing, because relays seem to be a harder to diagnose and more common failure element than the stalk switches and motors/gear cases.

If you suspect the wiper motor and the switches in the gear case, by al means remove them and plan a full bench service. The original grease in the gear case has long since turned to soap/wax, so even a basic clean and service with new grease will work wonders for noise and smoothness, not to mention the avoided wear. Clean and inspect the contacts on that wiper-parking switch too. It gets a workout every time the relay drops voltage to the motor; not just when you turn the wipers off, but at every intermittent wiper operation pulse from the relay. This effort is probably worthy of a ten-year maintenance interval regardless of whether you use the wipers, as the oil drains out of the grease thickener regardless. Reminds me that mine are due again.

Ditto window and sunroof motors and gear cases too, while you have the grease out. It's a slippery slope...

[944er]

I’ll pull the relay sometime this week, and see what happens to the wipers when I do. So if I pull the relay and the wipers turn off that tells me that the relay needs to be fixed?

Actually, it's a bit more complicated than that. If it still runs, then it is definitely the switch. If it stops, there are a couple more tests that will have to be made to pin down the source. Lets take it one step at a time.