S40 haunted wipers!!

[south coast]

Originally Posted by canis

I don't know this model, but I've an idea nobody has mentioned so far:

Most wipers have an auto-park feature, meaning that if they're not parked they can still get power to operate even if the switch is turned off, so they can return to their park position.

At the park position, this 'parking power' is stopped obviously, or the wipers would carry on. Might the brass track which enables this have come adrift somehow? Or have something metallic caught in it? Even water perhaps?

If the brass track which allows this parking to occur is occasionally making contact somewhere it would send the wipers out of the parked position - where they would obviously be an unparked position and continue on until they are parked again?

Just an idea.

I'd open the motor mechanism and take a look at the brass contacts. Give them all a good clean up and see if that improves things.

Following your suggestion and this related (although Mercedes) YouTube vid..

https://www.youtube.com/watch?v=mfqExxuwqyA

..I took the motor apart and cleaned these bits.

Am I on the right track? I suspect not.. I'll put the fuse back in and go for a drive

[andy_d]

those brushes look,, "not quite right" ,,and the stator is Rather worn,,
id look at making the bush ends "flat" not cupped as they are, clean out the stator Gaps (get the black gunk out) spin the motor and take the high spots off the contacts, then clean it and make sure there Are gaps between each segment

or gen volvo wiper motor n replace,,

edited to add pics that may help with the wear,,,

[south coast]

Originally Posted by andy_d

those brushes look,, "not quite right" ,,and the stator is Rather worn,,
id look at making the bush ends "flat" not cupped as they are, clean out the stator Gaps (get the black gunk out) spin the motor and take the high spots off the contacts, then clean it and make sure there Are gaps between each segment

or gen volvo wiper motor n replace,,

edited to add pics that may help with the wear,,,

Thanks for that.

I've cleaned it up a bit , but I think it might be time for a new motor

[andy_d]

you have the motor to see clearly and match its wear to the guide pics,, so you can say better than me,, the brushes look "cupped" compared to what im used to for brushes
doubt we can get replacement brushes for these easily, and it maybe costly but a gen volvo motor will fit,will work etc and be far less aggro to fit than finding the right bushes , fitting and rebuild onto the worn comm

[canis]

You've gone a bit deeper than I was meaning there. Although the stator and the brushes do look worn, with the motor working when you need it to I doubt that's the culprit for your wiper haunting.

Mechanically, the motor is attached to a gearbox out of which protrudes a crank arm, which is what moves the rods and ultimately the wipers. Inside the gearbox will be a switch of some kind, whether it's a brass track of microswitch or something similar, but it's necessary so the wipers know when they are parked.

This is the only image I could find to explain what I mean. It's not a Volvo, but the idea is there:



The top half of the diagram is a topographic description of how the wiper cam (in this case) switches the motor on and off, so they can park themselves when you switch them off.

The bottom half shows the motor driving a larger wheel, which will actuate a switch when the wipers are in their parked position. This is the piece I meant, it's inside the wiper's gearbox. If this switch (of whatever nature) has become faulty, it could allow the wipers to operate even when the driver's stork is in the 'off' position.

I'd look in there.

[canis]

You've gone a bit deeper than I was meaning there. Although the stator and the brushes do look worn, with the motor working when you need it to I doubt that's the culprit for your wiper haunting.

Mechanically, the motor is attached to a gearbox out of which protrudes a crank arm, which is what moves the rods and ultimately the wipers. Inside the gearbox will be a switch of some kind, whether it's a brass track of microswitch or something similar, but it's necessary so the wipers know when they are parked.

This is the only image I could find to explain what I mean. It's not a Volvo, but the idea is there:



The top half of the diagram is a topographic description of how the wiper cam (in this case) switches the motor on and off, so they can park themselves when you switch them off.

The bottom half shows the motor driving a larger wheel, which will actuate a switch when the wipers are in their parked position. This is the piece I meant, it's inside the wiper's gearbox. If this switch (of whatever nature) has become faulty, it could allow the wipers to operate even when the driver's stork is in the 'off' position.

I'd look in there.

EDIT: Before committing to buying anything, you can test this theory by finding the switch and disconnecting (even severing if needs must) it's wire. However you do this, make sure you can undo it later. The wipers will no longer park, which means you'll have to switch them off at just the right position. It also means the intermittent wiper won't work properly, they'll get someway through their travel and stop dead, so during this test you'll need to stop using the intermittent switch position. It'll be a nuisance, but you only need to do it for a day or so - long enough for them to exhibit the haunted behaviour, or for you to feel confident they no longer will.

BUT, if the "haunted" behaviour goes away, then you know this is it. In which case you can either attempt a fix on the self-parking switch, or obtain a new one, or secondhand. The cheapest solution will be to find a way to fix it. The simplest solution would be to obtain an entire wiper motor plus mechanism and simply swap it.

[andy_d]

Unlike many other vehicles, the fault monitoring in the P1 CEM has a sensitive output current window threshold. The PWM regulation is a much lower frequency (around 82 Hz) than the typical 1-200 kHz found in other makes/models. Worse still, there is a poorly designed power supply filter in the sensitive Wiper Motor computer (WMM) that shares a ground connection with the right headlight – such that back EMF transients and stray EMI from unshielded high-voltage ballast connections can cause (potentially permanent) erratic wiper behavior.

The ground point in question is actually not near the WMM – it’s at the passenger-side strut – with a good amount of wire in-between. You can follow the ground path in the 2005 S40/V50 wiring diagram:

Page 26: The ground point 31/110 is listed as “Right MacPherson strut tower”
Page 59: The headlight (group 35) low beams, specifically right side 10/2, ground via junction 63/109 -> junction 63/108 -> ground point 31/110 (right strut)
Page 77: WMM (6/1) grounds through pin3 -> junction 63/108 -> ground point 31/110 (right strut tower). The CEM itself grounds at A:14 -> junction 63/12 -> ground point 31/84 (passenger side A-post)
Page 171: Shows the junction 63/108 is buried in the engine harness, on the right side, with a good amount of distance to the ground point 31/110

bumped into that info while looking at hid headlights,
now if you dont have aftermarket HiD units, you may think "yeah and so??"
id be checking the r/h headlight ground point for corrosion/other as its shared with the wiper motor as a "well buggger me id never have thought That would do this" which your haunted wipers seem to be heading in the direction of , as spikes /etc in the system can apparently fry the WMM (window module motor )

for the time/effort to check and "nope not that" ,, has to be worth a try ?

[LizardOfBodom]

Originally Posted by andy_d

... do this" which your haunted wipers seem to be heading in the direction of , as spikes /etc in the system can apparently fry the WMM (window module motor )

for the time/effort to check and "nope not that" ,, has to be worth a try ?

WIPER module motor , just not to confuse further, but fair play to you for suggesting checking that!
As said above, WMM and headlight wiring shares the same ground points, hence the unfamous WMM+HID issue and few people reporting fried modules. Before Andy, nobody actually asked you if you have aftermarked HIDs installed or any modification to headlamps by any chance?

[andy_d]

to be fair TBHW would be more accurate,, "the bloody haunted wipers" ,,

[south coast]

Originally Posted by canis

You've gone a bit deeper than I was meaning there. Although the stator and the brushes do look worn, with the motor working when you need it to I doubt that's the culprit for your wiper haunting.

Mechanically, the motor is attached to a gearbox out of which protrudes a crank arm, which is what moves the rods and ultimately the wipers. Inside the gearbox will be a switch of some kind, whether it's a brass track of microswitch or something similar, but it's necessary so the wipers know when they are parked.

This is the only image I could find to explain what I mean. It's not a Volvo, but the idea is there:



The top half of the diagram is a topographic description of how the wiper cam (in this case) switches the motor on and off, so they can park themselves when you switch them off.

The bottom half shows the motor driving a larger wheel, which will actuate a switch when the wipers are in their parked position. This is the piece I meant, it's inside the wiper's gearbox. If this switch (of whatever nature) has become faulty, it could allow the wipers to operate even when the driver's stork is in the 'off' position.

I'd look in there.

EDIT: Before committing to buying anything, you can test this theory by finding the switch and disconnecting (even severing if needs must) it's wire. However you do this, make sure you can undo it later. The wipers will no longer park, which means you'll have to switch them off at just the right position. It also means the intermittent wiper won't work properly, they'll get someway through their travel and stop dead, so during this test you'll need to stop using the intermittent switch position. It'll be a nuisance, but you only need to do it for a day or so - long enough for them to exhibit the haunted behaviour, or for you to feel confident they no longer will.

BUT, if the "haunted" behaviour goes away, then you know this is it. In which case you can either attempt a fix on the self-parking switch, or obtain a new one, or secondhand. The cheapest solution will be to find a way to fix it. The simplest solution would be to obtain an entire wiper motor plus mechanism and simply swap it.

Thanks for this.

I think this is a bit more than I am comfortable with to be honest. But I think a whole new unit can be sourced reasonably cheaply, if necessary.

Strangely, after cleaning up the inside of the motor, the problem has not resurfaced YET !

This could well be coincidental though.