Trying to debug a non-functional rear wiper. There are 4 wires going to the motor assembly but I don't know what each one is. Does anyone have a wiring diagram and/or the required current and voltage for each one?

Its not simple to a non-electronics bod like me but this might help. With the wiring diagram you can see that both terminals 1 & 2 appear to be 12V supply but feed separate brushes (like a two speed wiper of 30 years ago). Terminal 3 has a cam operated mechanical park switch on the earthing side of the motor. Terminal 4 is an earth. All come from or feed back to the onboard supply computer which controls the wiper and which is further instructed by the wiper switch and intermittent switch. Both supplies from the OSC appear to be controlled by mini relays in the OSC and the park and earth also send feed back to the OSC. 

A simple test of the motor would be to pull the plug and supply 12v to terminal 1or 2 and earth terminal 4 with flying leads. Should run continuously with either. The motor itself may be dead but I think it's more likely to be an OSC fault

It is also possible that a VAG Com scan of the OSC would show a fault code relating to the rear wiper. Beyond that you could check continuity of the wires back to the OSC.

Edited 18 July, 20196 yr by LB123

Think that's the front wiper you're looking at LB?

Rear is simpler, can find info in a while if necessary.

Yes. My post is rubbish. Stuff for the front wiper. Mislead myself as 'rear wiper switch' is in the heading of the diag. Looking the rear motor diagram is even more obscure so I will slink quietly off into the background.

Thank you for picking that up.

Edited 18 July, 20196 yr by LB123

OK I found this thread:

and I intend to carry out the tests described therein as soon as I can. If anyone has additional info please feel free to contribute though.

Well turns out it was the motor after all, and opening up the case it is obvious why (water from a leaking washer hose has gotten into the gear mechanism and rusted it solid).

 

The motor assembly is labelled "Valeo 404.886" . However, when looking for used spares on ebay and other websites, the model 404.886B is more readily available. Is there any significant difference between the 404.886 and the 404.886B, and can I swap one for the other?

It's a wiper motor, what could go wrong?