Other The infernal wiper motor switching debate.

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Bobsticle

Bobsticle

De Villes Advocaat
Posts
27,632
Location
Manchester
I am attempting to remove the lucas wiper switch from my series.
Now its only a single speed switch with the push to squirt microswitch on the back. I am converting it to two shiny stainless steel push buttons. An on off button for the wiper and a momentary for the washer.
The washer wasnt a problem. Fetched a signal wire from the button to a relay and on to the washer motor, easy.

The wipers however are causing problems. I have downloaded a wiring circuit for two speed wipers using the original hardware and a couple of relays but cant find anything on a single speed switch. Its just starting to grate a little with the park facility not working at the moment.

Anyone seen anything on using relays with park.

It would be nice to get to the bottom of this one and post a how to in the tech section.
 
You don't really need a relay on the park, it's a permanent connection which carries no current until the switch inside the motor assembly dictates. And you only need a relay on the single switched feed if the push button that you're fitting isn't rated highly enough.
 
I am collating info on what each wire actually does for at the moment so I can do a schenam smeenati. Picture. I want to do an animated one so anyone can copy it. There seems to be a difference of opinion on the net :mad:


boguing said:
You don't really need a relay on the park, it's a permanent connection which carries no current until the switch inside the motor assembly dictates. And you only need a relay on the single switched feed if the push button that you're fitting isn't rated highly enough.
Click to expand...
 
Yep, some people go a bit relay mad, which is definitely better than the alternative.

If you put one on the park all you're doing is taking load off the ignition switch - which is designed for hefty loads - on the rare occasion that the wipers hadn't finished parking when you switched off the ignition.

I know that you won't be using a standard switch for the wiper, but if you've bought the right size then there's no need for one there either. You could put a big capacitor in for a posh soft start wiper though!
 
Its the problem of using an on/off push button with one 12v outlet I am trying to solve. The only way without complex circuitry I can think of is using relays to switch the relevant wiring on and off.
 
Ah - yes. Take it that you couldn't find a latching version of the switch? A relay would solve it - did you know that you can get latching relays?
 
Yes it latches in the on position. I just cant get my head round what wire needs to be on or off at any one time during the cycle.

So far I presume the two green wires supply a positive charge to the motor at all times. Either the green and red or the green and brown has 12v poured down it to start the wipers going but then what.
I keep trying to get my brain cell round it but there is so much conflicting info on the web its hard to find an answer.
Add all the bumf on other lucas systems and its all a bit blurry.
 
Nearly all wiper motors are the same. There's one wire for each speed of wipe, one earth and one permanent 12V. The There's a disc inside which spins once per wipe cycle, and it has a notch out of it and a brush touching it. When the wipers are off the brush is in the notch. As soon as the wipers start to move, the brush is in contact with the ring and is getting 12V from it. which it then supplies to the motor. Initially that means that the motor is being supplied 12V from the switch that you operated, and from the disc, but that's fine, it doesn't mind. When you switch off, the motor keeps getting power from the disc ring - until it gets to the notch and it stops.

This is why I said that you don't need a relay on the park - the switch is internal, so there's no way to use one anyway and again, it was designed to take that much current safely.

You need to take 12V to the park wire from anywhere that's fused and switched by the ignition, 12V from your latching push button to the main power wire, and then earth it. What is the spec of the switches you're using with ref. to Volts and Amps? Should let us know whether a relay is worthwhile on the main power.

I just checked your main thread, and you mentioned that it's a single speed unit - so the above covers it.
 
Last edited:
boguing said:
Nearly all wiper motors are the same. There's one wire for each speed of wipe, one earth and one permanent 12V. The There's a disc inside which spins once per wipe cycle, and it has a notch out of it and a brush touching it. When the wipers are off the brush is in the notch. As soon as the wipers start to move, the brush is in contact with the ring and is getting 12V from it. which it then supplies to the motor. Initially that means that the motor is being supplied 12V from the switch that you operated, and from the disc, but that's fine, it doesn't mind. When you switch off, the motor keeps getting power from the disc ring - until it gets to the notch and it stops.

This is why I said that you don't need a relay on the park - the switch is internal, so there's no way to use one anyway and again, it was designed to take that much current safely.

You need to take 12V to the park wire from anywhere that's fused and switched by the ignition, 12V from your latching push button to the main power wire, and then earth it. What is the spec of the switches you're using with ref. to Volts and Amps? Should let us know whether a relay is worthwhile on the main power.

I just checked your main thread, and you mentioned that it's a single speed unit - so the above covers it.
Click to expand...

I have all the gubbins sorted so should be able to wire something together. At the moment I simply have the 12v feed from the push button wired to a relay to supply the slow speed cable.
 
Blackburn said:
This any help
Click to expand...
I think this might work?????????????????????

wiper rewire.jpg


Any comments...................... or should I just wire it in and get the crumpets out.

FIRE.................FIRE................ DONT COPY THIS!!!!!!
 
Last edited:
Yes, that's a neat way of doing what the original set-up did. Don't forget that you might need the Earth to terminal 5 as per Blackburn's drawing.
 
Yeah if the switch on the left is an on /off not a momentary press its ok if I recall correctly the earth 1 is built into the motor / park switch.
If you want to go real posh fit an additional VW 99 Relay and another switch will give you intermittent wipe time being 7 secs or you can switch on then off and back on after upto 30 secs and the time will be what ever is the gap time.
 

Attachments

  • intermittent wipe .pdf
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Bobsticle said:
I think this might work?????????????????????

View attachment 96577

Any comments...................... or should I just wire it in and get the crumpets out.
Click to expand...

Ah no that cant work...............:oops:

In off mode the original switch connects brown/green to red/green
In on mode it connects green to red/green

This diagram in off mode connects green to red/green
In on mode it connects green to brown/green

Back to the drawing board......................:(
 
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