940 Headlight wiper motor repair?

The headlight wipers are disconnected on my 1997 945 since I've owned it because the passenger side wiper will not shut off and starts as soon as I turn the key. While it's not a big deal to me, I'd like to try to get them to work some time, especially since they put more and more salt on our roads each year during winter...

I guess the park position (if there is something like that?) of the motor is broken? Can this be fixed?

Thanks.

Maybe it's a relay.

Those should only activate when you activate the front window washer, if that helps narrow it down a bit

The headlight wipers do not use a separate relay, do they? Also the driver side one operates as it should.

Yes I know that they only activate when activating the washer, thanks. The one side starts wiping away as soon as I turn the ignition on, so that's why I thought it must be motor related.

I bet your rite although I have no.experience with the volvo units that saab wipers it's all in the wiper motor

Never had headlight wipers but have repaired the 'park' position in the hatch wiper in a 245.

First question is how is the motor getting power when it is driven off the same supply as the washer motors. Unless the motors are supplied with permanent B+ and a switched ground that doesn't make any sense. If they are you have a grounded lead that shouldn't be.

Time for a trip to the electrical schematic.

Inside the 'transmission' of the motor is the electrical connection in the form of a wiper that puts it into 'park'.

Good point about the power. That surely made me think now that you mentioned it. Will look for the schematic.

Thanks, I figured it would be some kind of "wiper" or small spring steel thing that it passes and shuts it off.

Apparently there is +12v at all times and by pulling the lever and activating the wash function, it grounds the motor and starts it (also the pump). Therefore my guess is that there indeed is an issue with the park position if the other motor stays parked when ignition is switched on. At least I know the motor works though!

I'm not an expert with schematics so I hope I read that correctly.

I read that as permanent ground and switched B+. Something between the ignition switch and the motor is turning on power.

Once had an issue with the wipers on a VW dasher (Passat) which turned out to be the chassis ground wire to the motor.

Anyone can chime in on the schematic?

I will have a look at this on the weekend, plan is to measure the pins in the connector and see what signals there are, but I just want to make sure I'm working with the correct circuit, so if there should be a permanent or switched +12v. If everything checks out fine, I'll go ahead and open up the motor.

Thanks.

. . . and the answer is . . . .

The wipe B+ is only applied when wash is called for . . . but the park power is available at all times.

Note that the wiper motor has two battery leads plus a ground. The incorrectly operating motor power leads are turned over or it is an internal wiper park issue.

Ah yes, that makes total sense. Now I see it too. Thanks, very much appreciated!

Just adding some comments to not let this thread die without solution, like so many on here.

Got to work on it this weekend. Actually found out that the RH wiper was not moving at all and just made a buzzing sound (didn't actually look properly before) and only when I gave it a bit of a push, it started moving 2 rounds and doing the park cycle.

The signals from the car checked out fine, so I opened up the motor and found that the main (blue) cog that moves the wiper has some teeth missing (right where it engages with the other cog in the photo). That's why it needs a bit of push to actually engage. I guess the wiper became stuck at one point and ground some of the teeth off while trying to move.

Off looking for a new motor then, since those single cogs are unobtainium.

Just adding some more comments as it might help some people later on, it's concerning the small motors in the housing.

I've spent so many hours on these things now that I can certainly call myself a certified wiper motor repair specialist?.

After I got a replacement RH motor housing from Sweden, both stopped working in the middle of the cycle and only moved very little (only a few days apart from each other). I tested them both with a battery and the motor in both seemed to be quite slow.

I couldn't find any information on the motor that was in it (even with the p/n printed on it), but I found one that looked identical and had the same dimension (Johnson HC310 - the Bosch OEM motor is a Johnson too) and just ordered a few of them since they were just 0.50 Euros each. They even have a Bosch number on them (a different one though).
Got them, replaced them and everything is working absolutely fine now, even with the motors with different p/n's. I just have the feeling the new motor has a higher RPM than the old one, but it's not too big of a difference (or maybe because the old motors are dying).

It's quite satisfying to make something work on the car that obviously hasn't for a lot of years and for reasons unknown. I'm quite enjoying the good light every time they go crazy with the salt on our roads again.

Below is a photo of both motors, old on top and new on bottom. Both can be used.
I didn't find a replacement for the broken blue cog though, these are probably not to be found anywhere. I guess you can use cogs from different wiper motors too, but there is a number on it which is the degrees how much they swivel (160? in case of the 940) and R and L are different.

Nice work! The part number difference is probably just an updated motor with the parts that break made more robust. Nowadays with 3d printing it shouldn't be too hard to replace the blue cog. Make a few and recoup a bit of your effort while helping other wiper motor users repair their setups.

Thanks!
I thought about 3D printing it and actually had lessons in AutoCAD during my apprenticeship, but I don't know if I'm still able to use it since it's been such a long time ago haha. But a workmate is a big CAD expert, so maybe he could draw it up for me for like a sixpack or so
But to be honest, I don't think there's really big interest in those cogs