Wiper wiring (RAM)

[JamesB]

I was expecting that a few fuses would need to be sacrificed!  Would be really appreciated if you could help with the diagram, I would be fairly certain that we have the same setup then as a rotary switch with the push button contacts was VERY hard to find so I think its probably the only one.  In pos 0 there are no contacts closed, Pos 1 contacts 1,2 and 3 are all closed and in position 2, contacts 1 and 4 are closed on the rotary switch I am using.

[aaronjb]

Relays.. you'll need relays. I'll see if I can find the wiring diagram I drew up - I have the same setup (probably the same rotary switch!)

Several fuses valiantly gave their lives to create said diagram 

[JamesB]

Unfortunately Kevin that's what I have already proved, the toggle switch uses a set of closed contacts when the wipers are off that feeds power to the park contacts in the motor.  The Rotary switch has no closed contacts in the off position so I will have to do something with a switching relay to externally create a set of closed contacts when the wiper switch is set to off.  It should not be impossible but fundamentally the rotary switch just does not work in the same way as the toggle switch and would have been used with a different wiper motor design.

[KevinW]

Will do, thanks Kev.

If you have the original toggle switch and a multimeter, you can draw out a truth table or logic table for the connectivity between the different tabs on the back and the 3 different toggle switch positions. You then need to look at how the tabs on the back of the rotary switch can be made to align with this. That's what I did.

[JamesB]

One more point - if you are using an aftermarket plug onto the wiper motor Lucas socket, double check that it makes contact with all connections. I had this problem which meant the park facility only worked intermittently. Required a bit of fiddling due to the plug being a poor reproduction,

Will do, thanks Kev.

[JamesB]

Graham, yes this was the sort of thing I was thinking of.  The park contact is accessible from the terminal block on the wiper motor which is a GEU 7708.  I think with a bit more effort I will get a working solution.  Kevin, I know the washer button should be separate but as you say, they are not much use and this switch (which cost me £90) seemed to offer both originality in terms of looks and the washer function as well.  Just one of those things where I did not think it through quite enough in the planning stage but one way or another I will get it to work.  Graham would you be prepared to sketch a cct for me?  This MGB info page describes the setup I had (toggle switch version).   http://www.mgb-stuff.org.uk/wiper3.htm

[KevinW]

One more point - if you are using an aftermarket plug onto the wiper motor Lucas socket, double check that it makes contact with all connections. I had this problem which meant the park facility only worked intermittently. Required a bit of fiddling due to the plug being a poor reproduction,

[Graham Heatrick]

Hi James. Assuming the wiper motor is connected internally to the park contact & the park contact is accessible as a terminal in the wiper connecting block then we should be able to sort it. 
The motor should require a 12v supply via the park contact so when this contact opens the motor stops (can leave the 12v supply to this even while parked). If so then a relay from your normal wiper switch could do the job.
A possible solution - connect the relay coil to the normal 'wipers on' supply from your wiper switch (so the relay energises when you operate the wipers) and connect a fused 12v feed to the normally closed (n/c) contact of the relay. Then wire the other side of the n/c contact to the parked contact terminal/connection.
This way, when you switch the wipers off the relay will de-energise switching the 12v power to the motor via the park contact. The wiper motor should then continue running until the park contact opens. Make sure the relay supply is fused correctly as per Chris's comment.
If the park contact is not connected to the motor internally then some extra wiring would be needed to link the park contact to the motor.
Good luck with getting it working🤞

Graham

Thanks for taking the time to have a think about this for me Chris.  I am still messing with different layouts for relays etc so will continue to try that route before taking the switch apart.  I did talk to a guy local to me who was a circuit designer for the motor industry, he has said that he will take a look, but if he can't resolve it then yes I think you may be right that I will have to modify the function of the switch.

Good point about the park contacts, no I had not thought about it.  With no wiper arms on then I guess a 5 amp fuse should be OK for testing and should also protect those contacts.

[KevinW]

I've got an original set-up on my car with the rotary switch. I bought a NOS switch originally - load of rubbish, it failed. I then gulped and forked out for the £75 switch that Holden sell - it works. Thought its price was a bit of a swindle, but then on inspection realised its hand-made/assembled.

If you want to be authentic, then the only way forward is a Trico hand-pump switch for the windscreen wash action, which is what I have- its crap! However, 427 S/C and 427F/C cars never had any windscreen wash fitted anyway, it was only fitted to the 427R Street cars (that had no sidepipes, roll-over hoop or bonnet bulge).

But to get back to your original point, the wiper park facility is located on the motor, not the switch. If your motor doesn't have this, then you are going to have a very hard time making it work, unless you build some electronics. These old motores came in single speed, twin speed, and twin speed with park facility variants. And if I remember correctly the type you need should have a 5 pin lucar plug on the motor assembly. When you turn the wipers off the motor will 'know' that it needs to park the wipers.

[JamesB]

Thanks for taking the time to have a think about this for me Chris.  I am still messing with different layouts for relays etc so will continue to try that route before taking the switch apart.  I did talk to a guy local to me who was a circuit designer for the motor industry, he has said that he will take a look, but if he can't resolve it then yes I think you may be right that I will have to modify the function of the switch.

Good point about the park contacts, no I had not thought about it.  With no wiper arms on then I guess a 5 amp fuse should be OK for testing and should also protect those contacts.

[Chris]

Have had a look at a few rotary type switches, Durite do one with self park but does'nt seem to have
the wash function.
My thinking is that the switch you have is a nice looking old one and the new ones just don't cut it !
If you can dismantle your current switch with relative ease and introduce the extra contacts, that may be
your best solution.
Chris.

[Chris]

I am a auto sparks by trade and have experience with these types of wiper motors with the old switches .
What I would first advise is that you need to make sure that the fusing is correct as you are playing around
with ideas on how to make the switch function to your requirements,
The problem could be that if you are not careful you could easily blow the self park contacts on the motor.
I quite sure you are already aware of this but thought it could be worth informing you of the possible
hazards, you don't want to let the "magic smoke " out !
In the mean time I will try and come up with a sensible suggestion, would be easier if on site though.
Chris.

[JamesB]

So...I spent weeks making a nice new dash for the car and managed to get all original type switches without first doing my homework.  The RAM uses an MGB wiper motor, this motor has the park wired through the switch which in the off position closes 2 contacts to park the wipers.  The new (old) rotary switch does not.  in the off position there are no closed contacts.  I am fairly useful at wiring and have wired up everything on the car or have drawn up the circuits and know that they will work, but I can't get my head round a way to make this work. I am not going back to the original toggle switch as I have made the dash to suit the correct rotary (which also has a push for the washers).  So one way or another this rotary switch has to work.  I looked at adding a switching relay to close 2 contacts when the switch was off but an auto electrician I know said that will not work as the it will be fed back from the motor....  I have all the relevant info on the wiring and switch function, is there anyone who is more experienced than me who could take a look and see if they can come up with a solution.  One way or another its going to work.  I could take the switch apart and see if I can make up a new board which will have 2 contacts closed in the off position but I would not mind betting that the wiper positions etc will preclude that from working so before I try that I thought I would ask here......