Rear wiper wiring

[Blackdog]

The rear wiper on my 07 plate V70 has stopped working.

I have checked the fuse and that is OK.

So I'm thinking I have a broken wire in the loom and most likely the earth as neither the intermittent or continuous settings work.

There are three wires going to the motor, white, yellow and black.

I presume that the black is the earth but can someone confirm this before I start cutting the wires to run a seperate earth.

Thanks.

[Harvey]

http://i1168.photobucket.com/albums/r499/harveysr/Mobile%20Uploads/2017-10/20171003_200619_zpsecdekhd5.jpg (http://s1168.photobucket.com/user/harveysr/media/Mobile%20Uploads/2017-10/20171003_200619_zpsecdekhd5.jpg.html)

http://i1168.photobucket.com/albums/r499/harveysr/Mobile%20Uploads/2017-10/20171003_200700_zpsmwtnjv7r.jpg (http://s1168.photobucket.com/user/harveysr/media/Mobile%20Uploads/2017-10/20171003_200700_zpsmwtnjv7r.jpg.html)

SB is black
W is white
Y is ..yellow

[Blackdog]

Thanks Harvey.

Looking at that I'm glad I don't have an XC90.

If I'm reading that right it would be a mass of white wires.

[LeeT5]

I would probe the motor plug with a live to confirm it's not the motor before you go chopping wires.
Easy enough to check continuity on the earth.

Likely to be a broken wire in the lume where it passes through the tailgate and into the body.

[MoleT-5R]

As Lee has said above, have you tested all the connections with a multi meter for supply voltages and and continuity on the earth, as if it's anything like my 850's, it's the mechanism that seizes and swapping for another know item could be a quick way to pin point the issue. That is if you have access to one as, you don't want to be cutting up your wiring harness if you don't need to.

[foammanmark]

My rear wiper on my 98 R had stopped working when I recently bought her back. I sussed out that with the wiper switched on and a little gentle persuasion, it works again. Did it again only yesterday but is now working again after heavy rain meant it had some exercise.

[Blackdog]

Motor is working as I bought a used replacement that was tested in front of me.

Ised a multi meter to pierce the insulation and have a 12v on one of them.

So it looks like a broken earth.

What i will do though just to totally confirm prior to chopping is run a wire from the battery negative to the motor casing and see if it works.

[LeeT5]

Motor is working as I bought a used replacement that was tested in front of me.

Ised a multi meter to pierce the insulation and have a 12v on one of them.

So it looks like a broken earth.

What i will do though just to totally confirm prior to chopping is run a wire from the battery negative to the motor casing and see if it works.

I doubt that will work as it's probably earthed internally.

All you need to do it set your multimeter to 'Ohms' and check you have an Earth (continuity) in the other wire/s that are not 12v (live) or 12v (switched live).

If you have access to a power probe, you could then, once you've established the live in and earth terminals on the motor, using the power probe give the motor a live and earth. If it doesn't work then you can be 100% it's the motor.

If you have live and earth from the wiring harness, then the motor should work.

[Blackdog]

I know the motor is good as I have seen it running. When demonstrated it was earthed via the casing.

[MoleT-5R]

I know the motor is good as I have seen it running. When demonstrated it was earthed via the casing.

So this is a replacement unit.?

[Blackdog]

Yep. The original stopped working so in my infinite wisdom I took it apart expecting to find a seized gear mechanism. This was not the case so I the decided it would be a good idea to check the brushes and rotor. I do not recommend this. Brushes and springs everywhere. So off to the brealers for a replacement. Put it in and it too did not work. Back to the breakers and ir was tested in front of me and shown working. As I said the fuse is good and 12v to one of the supply cables when switched on, hence why I think the earth wire is broken.