bureau13

This is on my '82 931, but based on what I've seen with this car, I believe the wiper setup is probably the same as the early 944.

I had previously noted that the intermittent wiper setting was doing nothing, so I replaced the relay for that, and things worked. Then, it didn't rain for a while, and I forgot about it. Well, last week I got caught in some rain, and damned if ALL the wiper switch settings are now dead. I assumed I blew a fuse, which I did, but when I put a new fuse in it got very hot very quickly, and has probably blown again. In any case, no wiper functions suddenly started working. Something else is going on.

Looking at the wiring diagram for the wipers, it's confusing, but I think I've narrowed it down to either the switch, the intermittent relay (again!) or the wiper motor. Yes, literally that is the entire circuit lol. Given that (a) the switch and motor seemed just fine before, and (b) my new relay is actually a used relay, I'm thinking I'll replace that and see what happens. Anyone else had this issue and discovered anything interesting while diagnosing, that maybe I should take into account?

DSMblue

With the fuse getting hot so quickly, you might check for a grounding issue. You could try to hook the motor directly to the battery to verify motor functionality and eliminate that as the issue.

bureau13

That's a good idea, and would seem to be a fairly easy test.

bureau13

I checked power at the connector to the motor. I'm not sure of the pinout, but I see ground on the center, +12V on one pin whenever any wiper position is on, and then depending on which position the switch is in, I also see +12V at one of the other positions. I cleaned all the connectors although they didn't look bad, but no joy. The wiper motor itself does nothing. I suspect it's dead.

Is this the same motor as used in, say, early 944? Any other cars? Most places say they're out of stock but Pelican supposedly has one. For $700+! Honestly, I don't need wipers that badly. If I can I'll go used...and that gets easier if it shares the same motor with other models...

Gregs04.5

The motor for the VW Golf Jetta etc. will bolt right in, and can be had for less than $30. the pin out is different, as is the plug. I did get one a while back, but have not found the time to figure out the wiring, as mine is still working, but noisy. (and I am as far from being an electrician as one can get)
Anyway, look into this, may save $670, and If you get it to work, please pass on the wiring.
Greg.


Link Thingy look here for ebay wiper motor

Schmooey

I had a similar issue and it turned out to be the switch on the column. When I took it apart, it was melted at the connector. I bought a new one (from VW, as it was a lot cheaper and the correct color) and replaced it, and it worked again. There are two switches - one for the blinkers on the left and the wiper one, on the right. Easy to get to and replace, but as always, 34 year old plastic is brittle, so I went slowly!
John

bureau13

I considered that a prime suspect until I watched the voltage appear/disappear at the motor connector based on the switch position.

bureau13

Good info, I will look into that, thanks!

QUOTE=gregs04.5;15244644]The motor for the VW Golf Jetta etc. will bolt right in, and can be had for less than $30. the pin out is different, as is the plug. I did get one a while back, but have not found the time to figure out the wiring, as mine is still working, but noisy. (and I am as far from being an electrician as one can get)
Anyway, look into this, may save $670, and If you get it to work, please pass on the wiring.
Greg.


Link Thingy look here for ebay wiper motor[/QUOTE]

elgy

For noisy motors change the bearing... perhaps easier than changing the wiring and you then know that you have a good bearing.
From my 924S thread...
"Shortly after buying the 924S the wiper motor stopped working. I took it apart, cleaned and greased it and got it working again… but it made a horrible growling noise. So using
http://forums.pelicanparts.com/porsc...eanimated.html
… and from the 928 forum...
https://rennlist.com/forums/928-foru...-overhaul.html
I disassembled the motor and replaced the bearing between the motor and the worm gear. The hardest part was getting the bearing off the motor’s shaft and getting the new bearing on. Once it was all back together and installed it ran quite nicely."

bureau13

Update: The wiring was finicky but pretty straightforward. I was able to find a matching piece of harness w/ the connector, which wasn't really necessary but is better than trying to hook wires directly into the connector on the motor. From there it was pretty obvious which pins on the new motor were equivalent to the pins on the old. Hooked it up and everything works fine...electrically.

The problem is some very subtle mechanical differences. The output shaft on the motor is slightly shorter. When I bolt the motor up, I can connect the wiper linkage but it binds on the hex head bolts that hold the wiper motor to the frame. I tried to insert some washers as spacers, but that didn't work because the motor simply spins inside the linkage...there is not enough grip on the shaft with the spacer in place. So I'm at a bit of a standstill now...

931guru

A bench grinder will solve the clearance problem. 'That bellcrank is overengineered anyway.

bureau13

What would I grind though? It's not clear to me (I'm not good with fabrication, etc so this may be obvious to someone who is). I did see a thread elsewhere where someone replaced part of the linkage with something from a Fiat that cleared the bolt heads, but I don't have a garage full of old Fiat parts

Gregs04.5

If you take a little off the motor where the mounting bolts go (maybe 1/8" or so) in all three spots, it should clear.

edalenta

A little tip someone gave me a long time ago: Before you install the wiper arms, clip a spring-loaded clothespin to each spindle first, and then cycle the wipers to determine if you are really at the fully parked position.