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V70 rear wiper issues + solution

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Old Apr 28th, 2009, 10:17   #1
R-P
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Default V70 rear wiper issues + solution

Hi all,

Since I spend a lot of work on the rear wiper, and I didn't find a sticky on it, I thought I'd post this, as it is quite different from the one in the 850 forum.

It is a write-up that I posted on another forum, so please forgive the copy-paste action and let me know if something has to be changed. I will try to make it into a coherent posting...

Original problem description:
My V70 '04 's rear wiper doesn't work anymore. It only makes a ticking noise (sounds like a relay) coming from INSIDE the motor/gearsystem of the wiper. I think this is trying to switch it on to get it to return to the 'zero'position, which it is not atm.

It had issues before I think (it would stop at 2/3rds from left to right, then continue a second later and go to 1/3rd from right to left), but now it has failed completely.

Checked the hinge cabling mentioned as a possible culprit, but that is in pristine shape. Fuses are all OK.

The whole unit of my '04 model. Getting it out is straight forward and I don't have any pics on it (4 torx screws will take the bootlid-doorcard off (pull off gently as there are still pins keeping it attached to the bootlid), three 10mm bolts fix the motor, take off the washer-tube (gently wiggle while pulling), take off the wiper (flick the hinged plastic part up to reveal the 13mm bolt which you undo, wiggle the wiper (use the 'arm' of the wiper to exert force) to get it to slide off) and pull out the total motor assembly gently).


Issue in getting it disassembled: turns out you can carefully pull the spray-nozzle (the actual jets that spray on the window, 1" piece of plastic) out, and this means you can pull the entire water-tube out of the axle (beware of the tiny o-ring that closes this inner-tube of brass (? at least brass colored) from the rest of the axle!!!))



Both sides of the PCB. Clearly visible is a Diode (black round electronic component that will only pass current one way, so will stop any current from flowing through the motor if someone would apply the 12V the wrong way around) and the thermal fuse (silver rectangle next to the diode) that makes the infamous ticking noise by switching off when too much current is passing through it (and automatically restoring itself once cooled off).
Also visible is three contacts for the positioning circuitry (see pictures of backside white toothed wheel, this is where they attach) and two contacts for driving the motor.





White toothed wheel that is driven by the motor and turns a round motion into a back-and-forth-swinging-motion. Note the backside that features a simple system to 'tell' the assembly in which position the arm is. It's a very dumb system, it will supply current or not (probably to the interval-relais through the yellow wire), depending on whether the middle contact-sleeve is making a short to either the outside or the inner one. I heard a mention about the resting position of the arm not being the same: this makes it very plausible: the friction of the wiper to the window combined with the inertia of the whole system will determine the end-position. Not saying it is a bad system, but it is crude. And therefor simple, and therefor durable. But not nearly durable enough, or this thread wouldn't exist...


The three contacts that interface with the rear of the white toothed wheel.


A separate part that came out ofter thoroughly cleaning the o-ring groove: turns out this part makes up the o-ring groove (along with the entire housing of the assembly). Possibly I have tapped it in too hard, causing the o-ring to have too little room to properly settle, so as soon as I find a replacement o-ring, I will be taking this part out again, and next time will be mounting it with less force.


The actual o-ring (pardon the lousy quality of the pic... The measurements were 1.4mm thick and 12mm outside diameter, IIRC!!!!! Will try to get a replacement at work and will mention which size works best If I ever find out.





Couple of pics of the metal gears and the thing I always refer to as the "axle" (I hammered this out of the plastic housing: not the best of ideas, as I damaged the top a little):


Note the spring loaded ring on the pin that slides into the white toothed wheel:


Magnetic, so pulling it loose will feel like you're pulling apart some wiring... Also notice the bent tabs. If there is no need to take the motor apart: then DON'T!!!!! You will always damage the plastic that the tabs hook on to, so after doing this a few times, the plastic will be severely damaged!

The motor insides:

Also note the spring-ring and tab lying on the newspaper. Don't forget this when reassembling it (yes, I did forget... and had to bent the tabs loose for the second time...).
What this does exactly is not quite clear to me: the tab moves outward once the wiper arm changes direction and the spring-ring keeps it from falling out (this means the bulk of the motor actually moves 1/8th of an inch as well I think). So even though the white toothed wheel goes round and round, something in the motor shifts during this reversal of wiper-arm direction. Possibly this is build in the absorb the direction change and the accompanying forces. The wiper arm goes back and forth, the white toothed wheel turns around, and the part of the motor also moves back and forth..... ????? It has to do with the first part of the movement: the motor is "pushing", the second part, it is "pulling".
Just a wild guess...



Here's some extra info:

And the plot thickens...


After doing all the work mentioned above, it still didn't work, and I thought it may have something to do with the o-ring being old, or the axle unround.

So I got it out for the third time and did some measuring.
The motor used 3 ampere and the voltage at my powersupply dropped to 8 or 9 volts (it is a 3A powersupply). I then reopened the box that contains the PCB and rang the manufacturer of the current limiting switch. It does not have type-number markings on it, but they confirmed my thoughts that this may be on the bottom. So after desoldering the unit, I gave them the numbers and they gave me the specsheet. Which they would not let me place here.

But the essence is that it trips at 7.2 A within 4-10 seconds. Testing showed this was about right, and further testing showed it tripped at 3A after 2 minutes. Since my motor uses 3A@8 volts, it will simply never work, so I deduced the motor has to be faulty.

I did a quick test with two powersupplies paralleled and the motor (without the currentswitch in place) now used 3+3=6A at ~12V. And this was without any gears attached!!!!!
So I opened up the motor. Again. And as said last time: you have to fold away metal tabs and you can only do this so often, as they damage the plastic housing.

I tried to reassemble it away from the gearhousing so I could turn it to feel the friction, but this didn't work well for two reasons: (1) the upper bearing is fixed in the gearhousing (and without it the magnetic force pulls the two motorparts together, so you cannot determine if it runs freely), and (2) the axle of the motor wouldn't go through the bottom bearing.

So I also removed the lower part of the motor housing (once again: tabs, even worse ones than the ones holding the motor attached to the gearhousing...). The bottom bearing was misaligned. After thoroughly rotating, lubricating and fiddling, it seemed quite smooth again.

I reassembled the bottompart, attached the motor to the gearhousing, whacked all tabs into place and hooked the motor up: succes: currentdraw at 14V: 0.7A. About 10 times less (!) than half an hour earlier.
Resoldered the current-limiting-switch, and after hooking everything up in the car, I now actually have a working rear-wiper [thumbup]

So to recap:
My problem was the axle running from the gears to the wiper.
When fixing this I may have added a new problem, or may have overlooked an existing (possibly bigger) problem: the bearings of the motor.

Two pics of the top-bearing. Not sure whether the axle is supposed to rotate inside the shaft or that the 'ball-jointed' bearing is supposed to rotate within its outer part as well. The fact that it is somewhat of a ball-joint (?) was the reason it was misaligned at the bottom of the motorhousing, and I couldn't get the inner-part of the motor to slide in. That's what forced me to open up the bottom part, of which I obviously have no pics, as I got carried away and forgot all about pictures. Both bearings, top and bottom, seem identical.

And at a slight angle


The thermal current limiting switch. The 24V3T marking is NOT a 24 volts 3 ampere slow-tripping marking, but a date Week 24 in year 03 probably. The "T" is the plant where it was made.



Two more pics of the motor. Take note of the V-shaped tabs on the left side of the pic holding the plastic bottom part attached to the metal middle-housing... Pita to open (vice works well) and close (hammered a pin inbetween to wedge them apart again, but you cannot put the metal middle housing into a vice while doing this, as you may deform it and screw up the entire motor...)



Hope this helps you lot, as this seems a pretty common problem. I have heard people getting good results from simply drowning the thing in WD40, but where's the fun in that...

Last edited by R-P; Apr 28th, 2009 at 10:52.
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Old Apr 30th, 2009, 13:44   #2
tedmonds
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Question Excellent post, but how did you get the motor off?

R-P, this is one of the most thorough posts I've seen on a forum, thank you.

Alas, I have a but: you start at the point where the motor is on the bench.

Are you able to bullet the steps involved in taking the motor out? I have a highl-level understanding, but would really appreciate a little more detail.

Thank you.
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Old May 26th, 2009, 11:32   #3
R-P
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Tedmonds: Sorry, didn't see your post sooner.

There is a description on how to remove the motor, but I didn't take pics on this. If I ever take it out, I will try to do so, but until then, this text along with seeing the bootlid in front of you (so you actually recognize what I am writing bout), should work quite well:
Quote:
The whole unit of my '04 model. Getting it out is straight forward and I don't have any pics on it (4 torx screws will take the bootlid-doorcard off (pull off gently as there are still pins keeping it attached to the bootlid), three 10mm bolts fix the motor it's not a 10mm bolt, but a size 10 head on an M5 bolt iirc, take off the washer-tube (the water-supply-tube) (gently wiggle while pulling), take off the wiper (flick the hinged plastic part up to reveal the 13mm bolt which you undo, wiggle the wiper (use the 'arm' of the wiper to exert force) to get it to slide off) and pull out the total motor assembly gently).
And obviously disconnect the powerwiring, the 'snap' that holds it in place can be 'unsnapped' from the bottom (it's at the underside, against the housing, you'll know what I mean with my crooked English when you have the item in your hand)

Hope this helps.
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Old Jan 15th, 2010, 23:34   #4
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Best post ever ! At least for a wiper motor issue ! Had the same problem with my 2004 v70 and decided to follow your tutorial... Actually the problem on my motor is the motor bearing. The motor body was filled up with all sort of dust... and I can barely turn the motor manually. I proceeded to a thorough cleaning and spray WD40 until the motor turns freely. Before having the linkage back into place, I connect the motor to the car and did some trials, as I did before any cleaning and greasing, and the motor turned freely and continuously ! Great news !!! So I reinstalled, linkage, motor to the car and wiper arm....and....it still doesn't work !!!! Arrrggghhh !! Actually it works much better but it stops time to time. The fact that the motor housing is hold with 4 tabs doesn't help the axle to bearing alignement to be accurate....
Thanks for your post, it's very useful !
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Old Jan 16th, 2010, 16:49   #5
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Quote:
Originally Posted by fgx318 View Post
Actually it works much better but it stops time to time.
Can you hear a clicking noise from the thermoswitch? That could be a clue there is still too much current being drawn. If you DON'T hear this, there may be something else wrong.

Let us know if you solve it... I'm still planning on trying to find out what the third wire on the connector does (interval?) and why my wiper doesn't go all the way back to its restingposition...

BTW: thanks for your kind words, always very nice to know my efforts are helping others. As other people's efforts are very much helping me!
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Old Jan 23rd, 2010, 02:45   #6
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Quote:
Originally Posted by R-P View Post
Can you hear a clicking noise from the thermoswitch? That could be a clue there is still too much current being drawn. If you DON'T hear this, there may be something else wrong.
I can clearly hear the thermoswitch click.

Quote:
Originally Posted by R-P View Post
Let us know if you solve it... I'm still planning on trying to find out what the third wire on the connector does (interval?) and why my wiper doesn't go all the way back to its restingposition...
I will having it disassemble this week end and let you now.

Thanks
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Old May 5th, 2010, 16:34   #7
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Thanks R-P.Your post is very helpful. Mine stopped and I could hear the overload switch clicking. The spindle was corroded in the housing. A bit of cleaning and some grease has fixed it completely. Humans 1 : Dissimilar metals 0
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Old Jul 21st, 2010, 11:28   #8
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Default Simpler

Hi Guys,

i thought i'd add in my experience on this one.

Had same problem - wiper stuck half way across and feint clicking from the motor.

Followed the instructions above and took apart the "gearbox" part of the mechanism but left the motor in place. I didn't fancy bending the tabs up and as the motor worked fine on its own didn't see the need.

Hammered the axle out (also damaged it a bit - should have put the nut back on before attacking it).

The mechanism on mine was full of rust and crud. Dismantled and cleaned it and put it back together with plenty of grease.

Looks like the problem with mine was leakage from the washer pipe somewhere within the spindle.

Had exactly the same problem on my 10 year old Audi A4 - although why is an Audi wiper motor assembly £80 and a Volvo one £220?

Now working fine.

So, for anyone thinking about tackling this job it's a lot simpler that the instructions above look - as long as the motor is OK, which it probably will be.

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Old Jul 21st, 2010, 13:29   #9
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Great post , really appreciate the time and effort you have put into doing this ( just noticed it was 2009 ) and never noticed it before , makes me wonder what other similar stuff there is if you search for it .

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Old Jul 21st, 2010, 16:27   #10
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Done all this, it is easier than it looks, because motor wasn't working but after freeing everything and reassembling I find the teeth are stripped on the white wheel and it now doesn't do the full cycle. Any suggestions?
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