Micra K11 Wipers

Autodata has no wiring diagrams for this model, sadly.

I'm guessing that it's unlikely there is a separate timer for the wipers; far more likely it is done either through the ECU, or a central timing module.

The Haynes diagram may well be correct. It is usual for the single pole changeover internal self-park switch to disconnect from the permanent feed, and connect the winding to earth in order to use dynamic braking to stop the wipers accurately in the same position each time. If you re- examine the diagram with that knowledge, it might make more sense.

You need to identify and test at the motor connection; if the signal to start the wipers is remaining on, the fault is external to the motor. If that is switching off OK, then it would seem that the internal switch may have failed.

Chris

I agree with Chris - the wipers are coasting past the 'brake' position and re-starting. To test the theory grab hold of an arm to slow it as it comes to the park position with the switch off.

If this confirms the problem then you have a bad earth.

A good generic diagram here. Good description of the motor becoming a generator :

"When the motor ends up as a short-circuited (sc´d) generator on switching off ."

Yours isn't being short circuited and the inertia could be allowing it to re-start. Note how it is the parking switch that passes current to the motor once it is off the park position.

Sorry - missed link:

Many thanks Chris and John.

I think that this is how it is supposed to work. According to Haynes wiring diagram the relay definately connects 12V to ground when not energised when switch is in intermittent position! I am sure that they got it wrong. It may very well actually be shorting the motor. One end of the motor is hard wired to the 12V fuse and switching is at the ground end(s). So it will not be a bad earth in the motor circuit, it must be isolated from earth and shorted so all at 12V in park position. I will pull the fuse and check what goes where with the multimeter and hopefully correct the wiring diagram.

I do understand dynamic braking and how it would help in this situation. I agree that this is probably what is happening.

Good idea to physically slow the wipers at park to see what happens. Sounds like it could very well be the parking contacts not connecting to 12V properly. It has to be that or the relay remaining energised which was my first thought.

I'll check on Saturday.

just disconnect the permanent live feed to the wiper motor, if the wipers then turn on and off with the switch (but of course they will not park) then you know it is a fault in the park circuit, if they won't work at all then it is a fault in the switch/wiring/relays

That's the term - Dynamic Braking.

I suppose the park contacts could be in need of some attention.

Ok, some progress.

It was not possible to stop the wipers as they travelled through park. The motor was definately powered.

Checks showed that the relay remains powered even with wiper switch at off.

Relay is controlled by timer module which I have found. It is stuck on back of wiper switch. Output of timer module measures 500 ohms to ground with the module removed from the switch.. This probably allows enough current to flow through the relay to hold it on after it has been energised. Now need to fault find the timer. It is fairly simple using a Temic U842B chip. The switch itself checks out ok.

Found the error in the Haynes wiring diagram. They superimposed two lines within the switch making them appear to be connected.

I ran out of time, so to keep the car in service I have put it back together with the connection to the relay left off. This allows it to work in normal and fast mode and also on pulling the stalk foreward so it is useable.

Will try to source a new chip in the meantime.

Thanks for all the suggestions.