Basic multimeter help troubleshooting rear wiper/washer motor on mk4 golf gti.

[cerebral]

Hey,

I got a mk4 golf gti a couple of weeks ago and neither the rear wiper or washer are working. Before I buy a new motor I'd like to test that it is actually a fault with the motor, so I'm gonna go to Halfords and buy a multimeter.

Ok my mechanical skills are very limited and my electrical knowledge is 1 or 2 on a scale of 100 lol Still I'd like to improve my knowledge and need you guys to help a little.

So I get that one of the probes goes to the power and the other to earth but I've got a couple questions.

1. Do I back probe? ( Do I need to buy thin probes for this separately or are they with most kits)
2. The washer motor has 4 wires green, green/brown I think, brown and brown/black. I'm guessing the green and brown power the washer and the others power the wiper or vice versa. So which is power? and which is earth, take it for earth I can just connect to a boot hinge or similar?

oh thought of another question, what sort of volts should I expect? any other advice would be appreciated.

Thanks

[itavaltalainen]

What is the 10th character in your VIN (this stands for the model year)?

I can then look up what the wires are (there are some changes in electrics over the years) and will also write up some instructions to test motor etc.

Does your front wiper work OK? Glove box light come on?

[cerebral]

10th letter of vin is a 1

Front wiper works fine but got no light in the glovebox. Checked the fuse (swapped it with another one)

Thanks for the help appreciate it

[itavaltalainen]

Brown = GND
Black-brown = live 12V (from fuse 27) only live with ignition on, comes from X-relay
Green-red and Green-white come from stalk - either GND or 12V depends on switch position

Check that you get live 12V on black-brown. Check brown for continuity to earthing point, then unplug connector from wiper stalk and do continuity check from stalk connector to motor connector in boot.

If they are all ok then wiring is ok. Next you should be able with motor disconnected to measure voltages from both green-red and green-white wires against ground whilst turning rear wiper on at stalk (which obviously has to be plugged back in).
If that's ok then it is motor, if not stalk.

[cerebral]

Thanks for that itavaltalainen, just been to Halfords for a multimeter and they've none in stock, the sent me to screwfix saying they have them and they're open till 6, they shut at 4 grrr!

Ok can I just check I've got this right in my head?

black/brown is always live (not on or off)
brown is ground or earth
Green/red and green/white only receive power when washer/wiper is turned on, so if I turn rear wiper on I should get a voltage showing on one of them?

I'm lost with the continuity test though, do  you mean take of the headlining and test the wires at different points between the stalk and motor?

Oh btw I do have light in my glovebox, didn't realise ignition needed to be on, just occurred to me to check and it's working doh!

Thanks again.

[itavaltalainen]

Black brown is live when ignition is on as it comes off x relay (and mentioned fuse). You have 12V there or should have when ignition is on.
The two wires from stalk should have either 12 or 0V when operated. Can't tell you from wiring diagram. Continuity check is simply checking resistance across the wire, this should be only a few ohms.

You can also try B&Q, motor traders, homebase, maplins et al. They should all sell multimeters .

[cerebral]

Ok think I understand that lol sure it'll become clearer when I get the multimeter and have a bit of a play around.

I'll let you know how I get on.

Thank you!

[cerebral]

Ok got the multimeter on it!

With only ignition on brown/black shows 12.6v nothing from the others.

With ignition on and stalk pushed forward for wipers I get the same.

With ignition on and stalk held forward for washer, I get the same plus one of the green wires (not sure if it was the solid one or green/white gives a voltage reading (think it was about 12)

So conclusion I'm thinking washer seems to be getting power, so is probably blocked. Wiper is problem either with wiring or stalk switch?

[itavaltalainen]

The washer pump motor is in the washer fluid tank, there is no electric connection for it at the back at all. All four wires are for the wiper motor. 
If you don't get water in the back check the pump in the tank is working. If it is then check for broken hose in the boot lid and hinges..... wouldn't surprise me at all if it's broken there and has flooded motor.

[cerebral]

When I try the rear washer I can hear a pump/motor from under the bonnet. I've taken the lower black trim off and I can't see any signs of a leak. I wonder if when the previous owner noticed it was leaking he pulled the hose out from the pump?

I've also taken off the upper piece of trim (the bit where the high level brake light is) and all appears ok there too.

Guess I should look up how to remove headlining as I believe under there is a weak point for the washer hose/joint. No staining tho, so I'd be a little surprised.

Thanks buddy!

Strange that I got a volt reading when the washer stalk was pressed, must of made a mistake, had my 2 year old running round at the time. I'll have to try again later.