Rear wiper problem after new tailgate with existing wiring

TTKT

Australian Member
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I recently got back my T6 from smash repairer, after fitting a new tailgate (no other visible damage).
They used the existing tailgate wiring harness. ALMOST everything works OK - but there's a mystery. Rear wiper would not work. Auto Electrician says there's a wire broken somewhere between the front and the tailgate. My opinion - not possible. Maybe, someone pulled too hard on the harness inside the van roof, and disconnected one contact only???

His fix: take a thin wire from the number-plate light to one wire on the wiper motor plug (one edge of the connector, I can't read the laser-printed wire code) - and he said to me, the wiper will work with the usual stalk - as long as you have the parking lights (or mains) on.

Well, it did that, for a bit. Then it became intermittent, juddering around like a dying electrical clock, quite unpredictable. Then back to "Normal".

On the phone, the Auto Elect man was quite bemused by this, couldn't imagine what might be the cause.

Instead of waiting for him to look again, I did this: (1) Replaced his very thin wire with a heavy-gauge one; (2) Cut the original wire from the motor to the harness (leaving the end in a terminal block so as to be able to restore the contact if needs be. So that there was no chance of conflicting signals getting to the wiper motor through 2 different wires.

The result - odd, but I guess acceptable: if the light switch is on (pos 1 or 2), then the rear wiper stalk control does bring it on OK, without any mid-range stalling or jerky/juddering/clock-type movement.

As I am totally mystified about the cause or the "proper" fix, any opinions/experiences would be appreciated by me.
Wiring diagram for the rear wiper motor would be helpful - 4 contacts for a motor - why??)
Thanks!



(I'm also going to try posting some of this as a new thread under "Rear wiper" when i can remember how to do that!)
 
At a quick glance it looks like the tailgate motor unit has active electronics so I think you have a permanent live, ground and then a intermittent wipe trigger wire and continuous wipe trigger wire from the wiper stalk.

Sounds like yout electrician patched in the permanent live from elsewhere.
 
At a quick glance it looks like the tailgate motor unit has active electronics so I think you have a permanent live, ground and then a intermittent wipe trigger wire and continuous wipe trigger wire from the wiper stalk.

Sounds like your electrician patched in the permanent live from elsewhere.
Yes he did - from the nearby number plate light. So it only works when lights are on. I'm going to look for another permanent live in the latch area. Thanks.
 
I'd double check why the original isn't working (assuming you haven't) - while you can't get to the rear coupling the diagram shows another coupling point in the A pillar you might be able to get to and see if the circuit condition there.

Do you have heated washers - as those are fed from the same fuse.
 
Hi - thanks for the suggestion. No heated washers. I'll try the A pillar, if I can get off the trim, a bit short on specific for this model here . . .
Original failure? - No idea. It could have been 10500km ago as that's how far we drove home after the hatch was smashed.
But while the auto electric man said he checked all the fuses, I am at a loss to know how he would have got to this one (#25, center row, near the bottom) as I certainly can't with existing tools. Will have to modify a pair of pliers I think.
(The auto electric man also said he had no idea why the cruise control would not be working, but I found today it was because he must have put a fuse back in the wrong spot after checking, a new 5A fuse in slot 37 fixed that.)
 
Given the original damage I can certainly see how the fuse on a permanent live might have blown in a short, and if there is a track record of mistaken fuses...

Good luck :thumbsup:
 
Thanks! Damn, I actually had the glovebox out today to tidy up dash-cam wiring earth point, I guess will take it out again tomorrow!
(PS you are talking of a Right-hand_drive version I hope??)
Regards, Tim.
 
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Thanks! Damn, I actually had the glovebox out today to tidy up dash-cam wiring earth point, I guess will take it out again tomorrow!
(PS you are talking of a Right-hand_drive version I hope??)
Regards, Tim.
If you look in the linked diagram it shows location for both versions :)
 
OK. The issue is now SOLVED. But thank you for the guide . . . especially to the terminal block location.
I checked the "A pillar" connection blocks. Confirmed that one wire (black/green) connects to the problem wire at the motor. So, there was NO continuity problem in the shell of the van.
Photos attached for rear wiper connection. (NOTE I did not try tracing the wires for the other 3 pins of the wiper motor connecter plug!)

As it turned out - Fuse access was a problem , solved with a hacksaw - see separate post using the words "fuse access".
The 10A fuse for the rear wiper motor, position number 25, WAS BLOWN - so the auto electric man who said they had checked them all, was basically lying. I replaced the fuse, restored the wiring to standard configuration, and the wiper motor now works as normal.

PS the fuse box access was restored by using a hacksaw to remove some plastic . . . crude, a bit like a farmer using fencing wire to fix a problem - but it worked!!!

TP20230910005_VW_van_Socket_wiper_wire_on_right.jpg

TP20230910006_VW_van_Socket_wiper_wire_on_right.jpg

TP20230910007_VW_van_Socket_wiper_pin_on_LEFT.jpg
 
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