Yeti 2010 1.2 Tsi Petrol.

FAULT

Rear wiper became intermittent.  Stayed parked when switched on or rear wash given a push.  Left on and go to wiper and give it a nudge and it behaved normally;  sometimes it would work normally strait away, sometimes if left on and driving along it would start working again.  Eventually it stoped working altogether and nothing ever started it

New wiper fitted by garage (at my cost I was busy doing other work) and new wiper works in a simple fashion. Great!  

What it does:- occasionally selecting reverse it will do one sweep;  Parks in one position (unlike previous new which used to park a little higher at first then after (was it two sweeps?) it parked in fully down position: switch on wiper and it does a few sweeps and parks (only ever in one position) then carries on doing one sweep at a set time till switched off.

I like to fix things so diagnosed possible loose connection, worn motor brushes etc.  I have now just had time to examine wiper unit. Plastic lid comes off easily,  must pull the washer jet off the wiper blade end first then remove the 9 T15 TORX screws.  Directly on the motor are 2 tag-strips sticking up that make with 2 terminals on the lid. Connecting a 12V to these runs the motor smoothly every time ( must connect + and - right way round to get motor turning in right direction). 

On the lid there is a box with a lid that lifts off and inside there is a printed circuit board (PCB) which obviously must deal with number of initial sweeps then time delays between following sweeps and the two different parking positions.

The 2 terminals above the motor connect along a channel to the PCB (2 little white dots at top of that channel running from PCB box to motor)   On the motor lid is the input socket with 4 terminals.  I have determined that what must be the negative (earth?) side of the motor's 2 pins (lower goes to the first terminal of the plug on the left looking at the photo and the top motor terminal is the +.  I can see where the 4 plug pins join and solder to the PCB (bottom of PCB) and where the 2 outputs to the motor are soldered to the PCB (top left of boar).

The mechanical parts inside all look in unworn condition and anyway I hate throwing away such units.

I am thinking of options: 

1.  Replace lid with PCB on it with new one;

2.  Replace PCB only after unsoldering old one.

3.  connect wire from plug to motor so wiper works as a simple on/off with the column stalk (ok so would be continuous but maybe one position would provide 1 wipe only).  Would this possibly damage any other circuit/control unit on the car?

 

 

I am retire electronics engineer and have worked on far more complex equipment to component level replacement.  

Has anyone got a circuit diagram of the PCB with a functional description/readings?  It might be an interesting challenge to repair it!

Does anyone supply the lid only with the PCB?   Does anyone supply the PCB only anyway?

 

 

I understand that there was a "known" problem with the rear window wipers. Certainly had it on mine, (although it's a 2015 model).

 

Luckily I got the motor replaced under warranty, and it's been fine since...

Have you tried changing the setting as described in the owner's handbook?

 

Quote

Each time after switching off the engine for the second time, the wiper blade of
the rear window wiper is tilted. This prolongs the life of the wiper blade.
Activation/deactivation
› Switch on the ignition.
› Push the operating level into the position 6 » Fig. 37 on page 52 five times in
succession within 5 seconds.
› Switch off the ignition. After switching on the ignition again, the alternative
park position of the rear window wiper is activated/deactivated.

 

Dens, Looking at the photo of the delay PCB, I suspect the issue may be caused by dry/cracked solder joints on the 2 pads feeding power to the motor. See marked up photo attached.

Try resoldering these.

I have the same issue with a 2010 Superb Combi. Now I will check the PCB on  my motor.

 

Hi. 

I second Ubermarc's suggestion of resoldering the large motor contacts. 

 

Production line reflow soldering of PCBs that have a mix of large and small components is always problematic.  Enough heat to deal with the "biggies" and it may be too much for the miniature stuff.  Back off the heat and the "biggies" may not wet properly.  Add in  a touch of vibration, and months or years later the weak joints crack all round.

 

Having said all this, damaged wiring looms in the vicinity of the tailgate hinges are by no means unknown, and could be killing the logic feeds to the wiper.  I'd want to be certain that this area was all OK before delving into the wiper innards.

On 24/06/2021 at 15:07, Stubod said:

I understand that there was a "known" problem with the rear window wipers. Certainly had it on mine, (although it's a 2015 model).

 

Luckily I got the motor replaced under warranty, and it's been fine since...

Same here