My rear wiper was working intermittently for the past few weeks and would come on at times by itself.  The washer jet is working when pushed forward but my wiper has stopped working altogether.  I have taken the motor off the back and tested it with a 12v supply on the outer pins and it works OK. I checked all the fuses in the cabin and none are blown. I even put the front wipers going and pulled each fuse one at a time but none of them stopped the wiper. I did this because on the display for the fuses there is no fuse in the slot thats marked for wiper. I have 12v in the wire supplying the motor . What else could it be 

Fractured cable in the doorloop bellows, otherwise failure of the canbus module contained within the wiper, this would be revealed by a VCDS scan, quite possibly the former as well but a MK1 eyeball is best.

Hi Steven and welcome to Briskoda.

 

The rear wiper will not operate if Yeti's electronic wizardry senses (correctly or incorrectly) the tailgate is open. This could point to a fault in the tailgate lock. But I agree with JR that the most likely cause of your problem is the known issue of broken wires within the bellows at the top of the tailgate.

Thanks. Tailgate is closed and working correctly as when I disconnected the connector on the lock it showed up on the dash as open when it was closed but returned to normal when reconnected.  Does anyone know what the 2 middle prongs are for on the motor as they don't do anything when 12v is connected. Are they for when you put it in reverse and it comes on automatically when front wipers are on. 

There's a 12V feed, an earth and two 'signals' that tell it what to do. These come from the BCM I think, but also run to the main washer reservoir motor. Will post you a screenshot of wiring in a bit.

No CAN connections involved.

Point labelled 104 comes from cabin fuse 6 (15Amp, ignition switched). Grey bar at the top is the BCM

 

21 hours ago, Breezy_Pete said:

There's a 12V feed, an earth and two 'signals' that tell it what to do.

No CAN connections involved.

 

The two "signals" are a twisted pair so are they not Canbus?

 

Linbus perhaps?

 

On the Octavia I thought it was a canbus node, in fact I seem to recall it having the terminating resistor for the network or maybe it was nearby?

21 hours ago, Steven1981 said:

Does anyone know what the 2 middle prongs are for on the motor as they don't do anything when 12v is connected

 

They are for the self destruct function (don't ask me how I know ) and as a warning to people like myself to stop flashing wire pairs with 12 volt and to move into this century by reading up to understand the distributed intelligence in modern vehicle Canbus wiring systems.

 

Although Pete may well teach me that the Yeti rear wiper motor is not a Canbus node.

Not any sort of bus JR, since they also drive the washer pump which is just a dc motor as far as I'm aware.

CAN pairs are explicitly labelled on wiring diagrams as CANH and CANL in my experience.

Single wire LIN also similarly marked.

4 hours ago, Breezy_Pete said:

Not any sort of bus JR, since they also drive the washer pump which is just a dc motor as far as I'm aware.

 

Do you mean the communications ("signals") circuit only goes from the BCM to the rear wiper and the washer motor so is not a "bus"?

 

I had cataract surgery yesterday so cannot read the wiring diagram in enough detail.

 

I just wanted to warn off the OP from flashing 12v across that pair of terminals.

Yes that's what I meant. 12V should be quite safe to apply anywhere since I feel confident that's what is supplied to the washer motor in either polarity.

 

No idea what signals make the rear wiper do its thing, but presumably brief enough or low enough voltage to not activate the washer motor (except when requested).

Edited 25 March, 20233 yr by Breezy_Pete

Ah so you mean the two wires in question are to power the rear washer pump but also carry a data signal, a bit like DLan or our French CPL?

 

Isn't the pump on the Yeti the reversible one at the front? Why would those wires go to the rear of the vehicle or is it a parallel circuit?

 

Sorry for the questions, it's a pain not being able to read the wiring diagram!

Yes, reversible pump at front.

Yes, parallel connected.

 

The two wires are labelled WW and INT where they go into the rear wiper connector. Wash/wipe and Intermittent?

 

I guess maybe if WW is 12V and INT  is 0V it will do a wash of rear window and a programmed number of wipes.

If both are taken to 12V maybe that triggers intermittent wiping until both go back to 0V? And the washer pump won't run cos there'll be no potential difference across it?