Wiper Wiring Diagram Help - Switch and Earth - Why?

I have been researching the Earlybay, dash-mounted switch, windscreen wiper system as I want to make the system work using a toggle switch (I have a toggle-switch fetish, OK?) and a way of controlling the slow speed to give intermittent control, probably using a variable resistor.

Anyway, I have found this diagram:



[Original Wiring Diagram Credit: Telford Dorr, thesamba.com http://www.thesamba.com/vw/forum/viewtopic.php?p=6189324&sid=751a1592f4952751b5f8a7df3f694ed3#6189324" onclick="window.open(this.href);return false;]

So, it seems a clever, yet simple circuit.

In the off position, pin 30 on the switch provides +12V to 53a, which is a cam-driven switch.

When the switch is turned to 53 or 53b, power flows to the relevant points on the motor for slow and fast speeds - Got it.

When the wiper-motor is half-way through its cycle (using 53 or 53b), the cam-driven switch is closed which allows power to flow through 53e and turn the Bosch Cube Relay (coil) on using 85 and 86. This in-turn energises the relay to connect points 87 and 30 in the relay together and power flows through to 53 to allow the wipers to continue turning until the cam-driven switch 'turns off', which turns off the Bosch Cube relay and stops power flowing through 87 and 30, meaning the wipers have now 'parked' - cool.

Right, the parts I do not understand (unless I have the above wrong too :lol: :roll: ):

Why does there need to be an earth on point 87a in the Bosch Cube Relay, which is a Normally closed connection? Why does the switch need the earth (31b to 31)?

I want to put a toggle switch in to cover the functions of 53a, 53 and 53b, so would the system still work without that Earth (essentially, no point 31)?

Wiring!!! :? :sad0049:

The earth is needed so that when the wiper reaches the end of its sweep the motor is earthed out and stops through magnetic induction.

If you remove the earth at park lead then the inertia of the motor will allow it to spin on until the segment picks up power again and it will re start the cycle.

For intermittent control you will need to fit a similarly wired relay control. An ordinary simple wiper delay circuit will get shorted out by the earth brake system.

Thanks for your reply Trikky

Trikky2 said:

The earth is needed so that when the wiper reaches the end of its sweep the motor is earthed out and stops through magnetic induction.

If you remove the earth at park lead then the inertia of the motor will allow it to spin on until the segment picks up power again and it will re start the cycle.

Click to expand...

Perfect, that is what I needed to know. Now I know what it does and why, I can include the Earth in my wiring diagram and the toggle-swtich setup.

*Goes off to read about Magnetic Induction* :anim_20:

Trikky2 said:

For intermittent control you will need to fit a similarly wired relay control. An ordinary simple wiper delay circuit will get shorted out by the earth brake system.

Click to expand...

So a variable resistor on connection 53, to basically stop the power flow for a set time, depending on where you turned the resistor to, will not be enough? :?

A normal add on unit won't work because when your intermittent circuit wants to power the wiper motor it will still be earthed - (hence it will short to earth). You need the intermittent cirquit built in such a way that it disconnects the earth before applying power to the motor, as per the original switch and relay setup.

Your alternative suggestion of using the interrupt on the existing power supply after the switch will work without causing a short to earth but then the motor will have no earth braking to make it park and will tend to sweep on.

If you don't want to build or buy a unit that will work with what you have there is another possibility. You could change the wiper motor for a more modern one that has low inertia and hence doesn't need an earth brake. It's a lot of hassle though.

Mr Trikky! Sorry for the slow reply, working too hard at the moment! :?

Trikky2 said:

A normal add on unit won't work because when your intermittent circuit wants to power the wiper motor it will still be earthed - (hence it will short to earth). You need the intermittent cirquit built in such a way that it disconnects the earth before applying power to the motor, as per the original switch and relay setup.

Your alternative suggestion of using the interrupt on the existing power supply after the switch will work without causing a short to earth but then the motor will have no earth braking to make it park and will tend to sweep on.

Click to expand...

Thanks for explaining.

Trikky2 said:

If you don't want to build or buy a unit that will work with what you have there is another possibility. You could change the wiper motor for a more modern one that has low inertia and hence doesn't need an earth brake. It's a lot of hassle though.

Click to expand...

Yep, I think I will try and keep going with this idea of building a 'simple' circuit to replicate the function.

Right, I think I need to look at this as two problems, problem 1 is to modify the system to work without the factory dash-mounted switch and use a toggle switch instead. Problem 2 is to integrate a variable / selectable intermittent function into that system.

So, problem 1 first.

Taking into consideration what you have said Trikky, in your opinion, would this work?



Using the EarlyBay wiper motor, the 53 Slow and 53b Fast connections are controlled by a On-Off-On toggle switch which feeds a relay carrying a higher power supply to the relevant cable.

When either the 53 Slow or 53b Fast connections are in the On position, power is also fed to a Normally Closed 5 prong relay (the same as suggested by Telford Dorr for the park function), which then 'Opens' 87a and breaks power to 53a. However, when both the 53 Slow and 53b Fast connections are Off, no power is supplied to the Normally Closed 5 prong relay and 87a remains 'Closed' and allows power to flow through to 53a and the park circuit.

The park circuit has not been changed apart from permanently earthing 87a, instead of making it switched. I am guessing that this would be OK as 87a on that relay would not activated until power is cut.

What do you think? :shadey:

As long as your intermittent relay mimics the existing system (by allowing the earthing of the motor at the end of its park sweep - and then switching off this earth before re-applying power for the next sweep) it should work fine. That's what the aftermarket ones do (by copying the earth switching that comes via the stock wiper switch).

Thanks for the help Trikky (again).

After some research, I found this stand-alone kit:

http://www.maplin.co.uk/p/velleman-wiper-interval-timer-solder-kit-ve03d" onclick="window.open(this.href);return false;



It provides a selectable 5, 10 and 15 second delay. Looking at the instructions, you can change those delay periods to be longer or shorter by adding a different sized capacitor.

Looks pretty neat and I should be able to install similar to Telford Dorr's as shown here: http://www.thesamba.com/vw/forum/viewtopic.php?t=413975" onclick="window.open(this.href);return false;. Although I think I will have to extend the switch to make it a remote switch to fit behind the dash, I will probably try and make it a..... yes.. yes.. A toggle switch! :lol:

That Telford Dorr seems to be exceptionally good with wiring. arty0047:

Have you looked here ? about 3/4 of the way down

http://www.speedyjim.net/htm/elec.htm" onclick="window.open(this.href);return false;

dubdubz said:

Have you looked here ? about 3/4 of the way down

http://www.speedyjim.net/htm/elec.htm" onclick="window.open(this.href);return false;

Click to expand...

Yes, another great resource

cunning plan said:

dubdubz said:

Have you looked here ? about 3/4 of the way down

http://www.speedyjim.net/htm/elec.htm" onclick="window.open(this.href);return false;

Click to expand...

Yes, another great resource

Click to expand...

similar here too [yes I was digging out the bookmarked pages!]
http://www.keithandsylvia.co.uk/tech%20pages/bay_intermittent_wipers.htm" onclick="window.open(this.href);return false;

dubdubz said:

cunning plan said:

dubdubz said:

Have you looked here ? about 3/4 of the way down

http://www.speedyjim.net/htm/elec.htm" onclick="window.open(this.href);return false;

Click to expand...

Yes, another great resource

Click to expand...

similar here too [yes I was digging out the bookmarked pages!]
http://www.keithandsylvia.co.uk/tech%20pages/bay_intermittent_wipers.htm" onclick="window.open(this.href);return false;

Click to expand...

Ha, I am clearly not the first to attempt this! :mrgreen:

hey you looked in here too right?

http://flowcon.us/td/MiscAuto/" onclick="window.open(this.href);return false;

dubdubz said:

hey you looked in here too right?

http://flowcon.us/td/MiscAuto/" onclick="window.open(this.href);return false;

Click to expand...

Hmm, thanks, but that website does not work for me.

It was not so much the diagram of what goes where, the original question was about the theory behind how it works, I needed to understand why the Earth was required in the parking system and as Trikky has pointed out, it is for 'Magnetic Induction' and stopping the wipers abruptly before they sweep on and reconnect the cam-driven switch which will start the cycle again.

Question for Trikky (or anyone else who would like to join in).



Looking at the park-simulating relay, the feed from 87 goes through the normally closed relay, meaning that 87a grounds that power through 31b.

Question: In the switch off position and the wiper parked, the park relay would also be 'off' and 87a would be 'closed' and allowing power to flow to ground (31b) - would this cause an issue as technically, you just have 12v constantly flowing through wire and straight to ground without being used by a component first?

That does not seem right? :|

Added power flow for clarity:



So, again in the off position, power would continue to flow like that, but that is technically a short circuit? I understand that it is needed to stop the wipers when parking by earthing their power supply immediately, but after they have parked, the power will continue to flow.

I am thinking that the wire would just over heat and burn or fuses would continuously keep blowing? :? :|

The "Bosch Cube Relay" you have there is a change over relay meaning in one state current flows from 30 to 87 and in the other state from 30 to 87a. At no time are 87 and 87a connected.

madman said:

The "Bosch Cube Relay" you have there is a change over relay meaning in one state current flows from 30 to 87 and in the other state from 30 to 87a. At no time are 87 and 87a connected.

Click to expand...

Got it, thank you.

In my mind I had the 'pivot point' of the of the switch in the relay going from 87 to either 87a or 30, but now you have pointed it out it seems obvious that it goes from 30 to either 87a (resting position) or 87!

:shadey:

Hi...i am a new user here. As per my knowledge If you remove the earth at park lead then the inertia of the motor will allow it to spin on until the segment picks up power again and it will re start the cycle.For intermittent control you will need to fit a similarly wired relay control. An ordinary simple wiper delay circuit will get shorted out by the earth brake system.

Hi All,
For intermittent wiper, I used simple wiring order..
The 12v out from delay relay triggers pin 85 of the bosch relay and 86 is grounded with pin 31 of the wiper motor..This connects pin 87 to motor pin 53 for low speed.. When motor starts moving , pin 31b gives + 12 V signal that is used for triggering another Bosch relay in which pin 30 is connected to pin 86 for ground. Positive 12 v from 31b is supplied to pin 85 of this second relay connecting pin 30 to pin 87 thereby giving negative signal to internittent relay 31b or signal pin....that instantly stops the wipers for an intermittent cycle at the park position until the relay again starts for another new cycle and on...