Electrical connector pins rear wiper motor?

[reg091]

Hi,

Looks like the rear wiper motor has failed again (last replaced about three years ago). Rather than go through the nightmare of accessing the fuse box I thought a simple diagnostic would be to put a meter across the connector and see if I am getting power.
 

1. Unplugged connector from the motor.
2. Connected multimeter negative to boot latch metal.
3. Switched on rear wiper (engine running).
    

There are four pins in the connector. I am getting 14v from one of them and nothing from the other three.

Am I good to assume that the motor has failed? (What are the other three pins for?).

 

Tried to find a wiring diagram online but it's a jungle!

 

[Breezy_Pete]

What year is the car please?

 

[reg091]

Sorry, stupid of me! 2016 1.6 TDi Hatchback

[Breezy_Pete]

The wiring looks like this, where the black/violet is the one you've measured 14V on (please confirm?). The brown is an earth. The WW and INT are the wires that select Wash/Wipe or Intermittent wiper operation depending on request from driver via stalk and BCM. I don't know as fact, having never measured, but owing to the fact that on some/many earlier models these two wires are parallel-connected to the washer motor at the screenwash reservoir, I recently guessed at the following command logic:

WW=12V, INT=0V gives a wash of rear screen for as long as stalk held, followed by a pre-programmed number of wipes.

WW=12V, INT=12V gives intermittent wiper function until stalk control cancelled.

 

If I'm right this suggests that one or more of the WW /INT/Earth connections isn't intact, or the BCM isn't receiving the stalk inputs. 

 

Edited 5 April, 2023 by Breezy_Pete
May not have been that wire

[reg091]

Thanks @Breezy_Pete that is really helpful. I shall have to do some more investigating. Cheers.

[Breezy_Pete]

Just had a thought. I've made an edit early in the above post cos I made an assumption that could be invalid. Please confirm/deny that the wire you measured at 14V was so coloured.

[reg091]

I'll check tomorrow. Thanks!

 

[reg091]

Question: I assume that the motor is "commanded" to turn one direction, then the polarity reversed and turn the other way? Or is there a gear mechanism that allows the motor to turn continuously one way?

[Breezy_Pete]

Pretty sure motor runs one way only, or stuff within it does any required supply switching.

 

[reg091]

Thanks, that makes sense.

[reg091]

FYI found this pic on another thread. Not exact same model but looks like they all work the same way:

[reg091]

UPDATE: FIXED 

First to answer @Breezy_Pete: yes, the wire with 14v is the purple/black one. Interestingly though that has 14v regardless of if wiper stalk switch is switched to wipe or not.

1. I pulled the motor from the car and stripped the motor part from the cam housing (cam teeth look okay) and put 12v across it - nothing.
2. I pulled the cover from the motor (simply bend four metal tabs) and didn't find anything blindingly obviously wrong (it turns freely by hand) but the commutator was a bit dirty. Brushes are wearing, but still making good contact.
3. I cleaned out all the old grease and gunk, cleaned up the commutator (and other contacts) with contact cleaner and reassembled.
4. Put 12v across it and it worked. So, seems likely it was the dirty commutator.
5. Stuck it back on car, tested and it didn't work! Then I realised there must be a boot switch to stop it working when the lid is open! Closed boot and working okay!

Motor is only about three years old, and the wear on the brushes suggests I will probably be replacing it at some point. But, saved myself £££ today!
 

Some pictures. Arrows/circles show contacts and dirty commutator:

 

Edited 8 April, 2023 by reg091

[Breezy_Pete]

Well done. Yes, the black/violet will be nominal 12V whenever ignition is on.

[vRSAnt]

I had identical problem but managed to find this thread and opened it up ( for 2nd time but this time using this had confidence to tackle the motor part / shroud itself).

All sorted.

Seems a bit of a rubbish design IMHO, why send water through a motor moving part 🤷‍♂️ Simply not very clever

[reg091]

Great, glad that it helped. Agreed, it was a poor design decison.

[reg091]

OP here, seven months on and it has failed again. Stripped it down and it is full of water, plus the teeth on the cam wheel have been worn away in one spot (seems the motor was turning but the cam was seized).

 

New one ordered from ebay 55 quid. Chinese copy, will see how long it lasts!