Rear wiper motor joys

[Awkward_Josh]

Hi guys, 

 

Have been following the threads about the faulty rear wiper motors, have tried my luck with electrics and have got no where, have decided to take the motor off... Have opened it up taking out the 7 little screws and I realised I now have no idea what I'm looking for... 

 

Any help? 

 

 

[pikpilot]

What year? and estate or hatchback?

Mine is totally different.

 

[Awkward_Josh]

Just now, pikpilot said:

What year? and estate or hatchback?

Mine is totally different.

 

 

Sorry forgot to mention:

 

2012 and hatchback... 

 

I was expecting something different myself having read the other threads about this. 

 

Have just taken the gear assembly outside of the housing and movement is solid. 

 

Not sure if I should be looking at the actual motor instead of the mechanism?? 

[Awkward_Josh]

Better picture attached 

[Ju1ian1001]

The mechanism's tend to seize up and strip the teeth, thats what mine did, replace with a new one from a famous auction site; my motor was about £70.

 

Good luck trying to refit the boot trim, it's a bugger, mine is "resting" in my MG ZR project car at the moment.

[Awkward_Josh]

Any idea how I would check the brushes in the elctricalAny motor? The mechanism itself seems fine... 

 

Failing that I'll pop it back on and cross my fingers 

[Awkward_Josh]

Have just checked and I can move the worm gear... Somewhat easily... 

 

I'm assuming that this is conclusive that it's an electrical problem, but unfortunately don't have a 12v power supply to test the motor directly.... 

[Guest]

Can you take a picture of the electrical socket?

 

Do you have a DMM?

[Awkward_Josh]

Assume these? 

 

Have just put it back on the car so not the easiest to take a picture of haha, 

 

Seem to have also got the clips in my boot buy not on the trim... Whoops 

 

And no, no access to DMM or anything remotely useful unfortunately 

Edited 19 April, 2018 by Awkward_Josh

[davidwhite]

Have you got a local security alarm company ( or engineer ) nearby a standby battery from an intruder alarm would do the trick as a 12 volt supply ( they are normally changed at circa 4 years you don't need a new one )

[Awkward_Josh]

18 minutes ago, davidwhite said:

Have you got a local security alarm company ( or engineer ) nearby a standby battery from an intruder alarm would do the trick as a 12 volt supply ( they are normally changed at circa 4 years you don't need a new one )

No such luck im afraid, most local one is a good 20 minutes away and I've had to stop tinkering to put my daughter to bed haha... 

 

Got a good mind to leave it as is, order a curry, have a pint and let future me deal with it 

[Guest]

Long story short...

 

If the fuse is ok and power is getting to the motor then there is a bad brush/commutator connection.

 

I'd say turn the wiper on and hit the motor repeatedly with a small hammer to try and shock the contacts good, unless you want to disassemble the motor to investigate.

 

The problem being I suspect the car is clever enough to know when the tailgate is open and so won't activate the wiper, tricky.

 

Even a good blast of WD-40 or similar into the brush end of the motor may just be enough to get it moving again.

 

It'll be a simple problem that will have seen many motors landfilled because most folks don't have the ability/time to tinker.

 

Maybe there's a business opportunity here... Wiper motors fixed for £10+postage! Cheaper than a new one and environmentally better.

[pikpilot]

The fault on mine was the same as that reported by others. Motor brushes stuck in their holders. Free up the brushes so that they touch the commutator and the motor works again. With the top lid removed (all the electronics are in there), you can test the motor by putting 12V on the contacts.

Hitting it with a hammer may be enough to disturb the brushes as they have push springs behind them and so give a tempory fix.

My view is that part of the problem is the design of the spring. As the brushes wear and get shorter so the springs extend and exert less force on the back of the brush. This coupled with the brushes being too tight a fit in the sleeves that hold them.

[Awkward_Josh]

Thanks for the advice guys, I want to try and fix it (rather than replace it) if possible, both because I'm tight fisted and don't see the point in scrapping a perfectly servicable part 

 

I wanted to have the actual electric motor part open last night but could not for the life of me figure out a way of doing it without damaging anything... 

 

Am I right in thinking the rubber end cap comes away from the metal casing to reveal the inner workings? 

 

And if so do you have any advice on how to get it off without damaging it? Had a go at levering it off but just ending up putting dents in the rubber, 

 

Cheers again for the help in this, it's much appreciated 

[Guest]

It looks like there are metal tabs which are part of the motor shell, prising them back carefully should enable the end cap to be freed.

 

I say carefully as I've seen some butcher the things and upset the geometry of the motor causing running problems.

[Awkward_Josh]

20 minutes ago, MicMac said:

It looks like there are metal tabs which are part of the motor shell, prising them back carefully should enable the end cap to be freed.

 

I say carefully as I've seen some butcher the things and upset the geometry of the motor causing running problems.

 

Cheers for that, I did try briefly but saw the rubber starting to perish under the force of the lever so stopped. Will try and wrap the lever (or try my trim removal tools but I have little hope of that working). 

 

Will give an update once I've had it apart. 

[pikpilot]

You can see the end of the commutator in your photo. Can you see if the brushes are actually touching the commuter. (Note that a gap of  a thousand of an inch will stop the motor working so look closely).  Just wiggling the brushes in their holders may be the only thing you need to do. I don't recommend releasing the tabs or taking the motor apart unless you know there is a mechanical problem with the two bearings.

[wertok]

Just wanna say that I had the problem that the wiper got stuck after a couple of wipes. Removed and opened the motor and found dry grease that I think made it hard to turn. Cleaned it and put some new grease in and now it works. I hope it stays this way!

Edited 25 May, 2018 by wertok

[labman1001]

My rear wiper swipes across the screen fine but stops on the return ... If I lift the  blade of the screen it works absolutely fine with no sticking or juddering showing to me it's not a seized motor or worn teeth but more like the motor is losing some oomph to pull it back over ....

[andreasw]

Did you get it to work? Im having issues myself and I want to see if I cant fix it myself!

[tomoliva]

Skoda Octavia Mk1 2004

 

Erratic rear wiper (very..)

 

Had a look...  saw that controller board  CAN termination resistor (120 Ohm) had the resistor layer blown off - but little / no other visual evidence of other escaping magic smoke - - soldered a 1/4 Watt  120R across the two middle pins and  - hooray! - it worked.....   2p and an hour fiddling about.

 

Bugger all grease in the gearbox so dolloped a teaspoon (she'll kill me) of grease in there.

 

You can of course test the resistor by measuring across the middle two pins on the input terminals - it should show 120 ohms   etc.....  

Edited 2 April, 2019 by tomoliva

[J.R.]

Well done you

 

Did the canbus comms error show up on a VCDS scan?

 

Thanks for a good reminder of something else to check when faultfinding, lucky it had not dragged down the canbus line.

 

A question, its been a while since I read myself up to speed on Canbus, I think that each leg had its own 120 ohm termination resistor, does that mean that the one for the rear of the car is contained in the wiper motor? If so a fault with that could affect tailgate locking, fuel filler flap, rear bulbs etc.

 

I recall measuring for the presence of the EOL (end of line) resistor, hadn't realised that it was contained within the wiper motor, that brings another warning, if you remove it to work on it expect many random electrical problems.

[tomoliva]

J.R.

 

Nah - didn't scan  - as there's so much talk about knackered brushes and bad lube etc., etc.  that pulling the motor for a poke about seemed sensible.

 

The standard CAN termination is 120 ohms across the ends of the bus data wires (i.e. one at each physical end) so a properly terminated bus will read 60 ohms. I've not seen the bus topology for the wiper control but erratic operation with a missing terminator is to be expected. 

 

Hiding the termination on the wiper control board - that's a little cheap...  you can see the missing film on the SMD terminating resistor - it should be black with numbers - just bare white pottery on that one.

 

Makes me wonder about hacking the speed control on a main wiper motor for a boat I have - but that's another day.....

 

 

 

 

 

Edited 2 April, 2019 by tomoliva