850 Rear Windshield Wiper

Post by **manovlov** » 10 Jul 2021, 23:47

Hy Buddies,

I need some advice to repair my rear windshield wiper. How do you test it ? May someone have the the electrical wiring ?

When i use the commodo, there no liquid that gets out on the window and the motor doen't work .

I don't know what to test exactly. The fuse is ok.

Thanks for the help that will bring here.

Manov

Post by **manovlov** » 10 Jul 2021, 23:56

Ok i found an electrical diagram : is it the right one , I don't felle comfortable to know how to proceed....

: Volvo 850 wipers diagram.jpg (136.02 KiB) Viewed 1226 times

Post by **jreed** » 11 Jul 2021, 05:47

It sounds like there may be two symptoms: the motor to turn the wiper blade back and forth isn't working, and the washer fluid pump isn't working. Is that correct? If both of them are not working, then it could be due to damaged wires in the hinge.

Post by **scot850** » 11 Jul 2021, 06:23

+1 on this.

If the motor is not working, check for broken wires as jreed says at the LH rear hing on the tailgate. With age the wires break there. It is fiddly to repair but is the most likely issue.

If you are not getting water, doe the pump run at all when you try to wash the rear window? If you do not hear the motor run it has probably seized. Again a common issue. I think the 850 is the same as the V70 and here are 2 water pumps. One for the front and one for the rear. The one for the rear is at the front of the windshield washer water tank. Tight to get into but it pulls out from the top of the tank. One you get it out you can run a 12V wire to it and see if you can jump it into life. You can open them up if you are careful and clean the motor and see if that gets it going again.

If the pump works but no water gets to the rear, if I recall there is a one way valve on the RH front inner fender on the pipe that fails with age preventing water getting to the back.

Neil.

Post by **Clemens** » 11 Jul 2021, 07:35

+1 on the wiring harness if the motor doesn't work or works intermittent. I was able to solder the brokwn wires back together without removing anything except for the plastic cover on the hinge

Post by **manovlov** » 11 Jul 2021, 10:41

jreed wrote: ↑11 Jul 2021, 05:47 It sounds like there may be two symptoms: the motor to turn the wiper blade back and forth isn't working, and the washer fluid pump isn't working. Is that correct? ...

yes.

Post by **manovlov** » 11 Jul 2021, 10:44

I will have time to look all these points on wednesay. I will keep you informed about this issue. Thanks so much Guys !

Manov

Post by **jreed** » 11 Jul 2021, 16:59

I also had the check valve (or one-way valve) fail on the rear windshield washer spray system. I removed it from the fluid line. My memory is that the check valve was located under the plastic trim at the back of the car near the tailgate hinges. There is now a short delay between when I activate the pump and when the fluid comes spraying out, but it's not a major inconvenience.

Post by **abscate** » 14 Jul 2021, 05:07

All of the electrics for the washer pump are up front, so that’s a separate problem from the hinge wiring.

Easy to trouble shoot, have a helper operate the switch while you look for 12 volts on the washer motor

The tailgate hinge is a typical failure on high mile/age vehicles

Post by **manovlov** » 14 May 2022, 11:01

Work in progress...

i have some power at the back of the rear wiper motor. But i don't ear the pump starting to work when i press the comodo switch.

I think that rear pump is probably seized and the motor too.

Neil says that it may be repaired. I will check it tomorrow.