Wipers only working full speed, not returning to park

[Volvophile]

Ever since the snow, my wipers don't work at all aside from the full speed function. They are not parking either.

I have done a bit of searching and similar problems appear to have been linked to the brushes in the wiper motors. I am just wondering how likely this is to be the case and does anyone have experience of replacing these parts?

The car is a 1997 940 by the way.

[Laird Scooby]

I'd check the wiring to the wiper motor/park switch and the fuses to start with. It's possible where you overloaded the wiper by shifting the snow with them that it poped a fuse somewhere.

[Volvophile]

I've tried replacing fuse number 15. That hasn't solved the issue so far.

[Laird Scooby]

Just checked the diagram for the later 940s (latest i can find is 95 on) and if you look at Pg 43 of this pdf, you'll see a thermal trip in the motor :

http://www.myvolvolibrary.info/Tech_...ction-3-39.pdf

Difficult to be 100% certain as it's drawn to slightly different conventions to the norm but would appear that it is related to the earth return on the parking circuit and/or the low speed wipers.

Might be worth trying to find this circuit breaker, if it can be reset then problem solved - probably!

Also check fuse 16, it doesn't show any connection from F16 in the fusebox but usually if it's nothing to do with the circuit the diagram relates to, other fuses aren't shown. However it shows F16 so might be worth checking on the off-chance.

[Volvophile]

Originally Posted by Laird Scooby

Just checked the diagram for the later 940s (latest i can find is 95 on) and if you look at Pg 43 of this pdf, you'll see a thermal trip in the motor :

http://www.myvolvolibrary.info/Tech_...ction-3-39.pdf

Difficult to be 100% certain as it's drawn to slightly different conventions to the norm but would appear that it is related to the earth return on the parking circuit and/or the low speed wipers.

Might be worth trying to find this circuit breaker, if it can be reset then problem solved - probably!

Also check fuse 16, it doesn't show any connection from F16 in the fusebox but usually if it's nothing to do with the circuit the diagram relates to, other fuses aren't shown. However it shows F16 so might be worth checking on the off-chance.

Thanks again, Laird Scooby !

That is a very helpful post.

[Jimsiss]

Mine did the same when my Dad operated it last year in some rain and left them on when he switched the car off. Resulted in me turning the car on to defrost the next day and it killed the wipers on intermittent. Luckily he is an electrician and we are a very experienced hands on family so fixing it was rather simple if not very time consuming to set it up properly.

To take it apart you have to take the wiper arms off (remove the plastic covers and unbolt, then pull the wipers off the screen into the upright position and rock it up and down and it'll break free of the taper holding it on) then pop the bonnet and undo the bolts holding the panel on the wipers are mounted through I think there are 3, 2 either side and one on the bulkhead which is a pain to get in afterwards). This then slides out (there are slots and pegs to slide it on) and you have access to the rest of the wiper mechanism, undo the bolts holding it in and remove the cover over the heater intake and remove the wires. The rest should drop out with a bit of wiggling.

The brushes are in the motor itself so you'll need to get a screwdriver in the slot on the outer cover and twist slightly to prise it apart, then slide it off the motor. You should now be able to see the motor internals, I think there was something to move to see where the brushes were (but it's been a while) check the plastic square holes, these contain the brushes. One will be the intermittent wipe brush, on mine it had overheated and slightly warped the plastic. Remove it carefully (don't pull the wire if they are stuck), then check for damage and make sure it slides freely in the hole.

You can see there is a plastic cover (I think you may need to remove it at some point, I did to check the park switch as I thought it was that), it's covering the cam and switch that tells the wipers when to park. This may be important to you at some point but if you do take this all apart you need to reset it all so that the wipers park correctly again, just be aware of this.

Reassembly is pretty much the reverse of dissassembly but you need to test the wipers once the mechanism is bolted in again, just loosely fit the wiper arms and check they work and wipe in the correct place, the mechanism has rubber bushes so there is some play when bolting it up. Getting the cover over the heater intake back in correctly and sealed with lots of strong sealant is very important, any leaks past that will drop water into the heater motor and wreck it (I had to reseal it twice to get it back to being water tight).

[Volvophile]

Thanks for that very detailed post.

Tell me, do you have to replace the warped part or can it be formed back into place? Also, is there a specific setting for adjusting the park?

I wish I didn't hit the wiper stalk now....

[Jimsiss]

It might just need freeing off in the hole or a small file taking to it just to square the hole up again.

To adjust the park to you have to adjust the cam position. But if you have the brush problem then it might not need adjusting, once the brush is freed it should park again.

[Volvophile]

I got to work on it today and have opened up the motor. I cannot identify which are the brushes in the square holes.

I have a picture attached.

Edit: Actually, I cannot get the picture to show. Apologies.