Intermittent wipe (again sorry) SEE ANDREW'S WIRING DIAGRAM

[JNC]

Can't get my head around why you can't wire a momentary switch in to existing wiper switch ? , if I wire a momentary switch directly to the existing switch by spurring the live to one terminal and from the other terminal to the supply from the existing switch to the wiper motor, will this work ?.

[SM25T]

Well ... I thought it would be as easy as that ..... but several fuses later, discovered it wasn't !! Some magical sort of relay soon fixed it.

[elie boone]

you can plumb in a tin top intermittent  wipe on the 2nd speed of the wiper motor but this leave you only with the first speed when it rains harder

[revilla]

The wiper switch is a more complex changeover type. In order to stop the motor dead when the wipers park, rather than allowing the motor inertia to run them on a bit, the parking switch switch shorts across the motor so you get electromagnetic braking. If you then switch power to the motor while is shorted you will just pop the fuse. To add a flick wipe you either need to use a changeover switch of the break-before-make type or a relay. Been playing with intermittent wipe myself today. Let me know if you want me to sketch a wiring diagram for a flick switch for you.

[JNC]

Yes please

[Wrightpayne]

Andrew

i think an alternate career of Caterham auto electrics technician is beckoning :-)

Ian

[revilla]

@Ian ... if only I could make good money out of it!

@John:

First of all, here is a link to an excellent article sent to me recently by Mechanical Moz which explains how the Lucas 2 Speed Wiper System works:

http://www.mgb-stuff.org.uk/wiper3.htm

I've taken the following diagram from the above article and adapted it to correspond exactly to the relevant wiring in the Caterham installation, so I've coloured the wires appropriately and also added in the connectors provided to allow for the installation of an intermittent wipe controller. These connectors also contain one green/black wire for the windscreen washers so I've added it for clarity even though it doesn't play any part in this. The diagram shows the wiper switch in the "Off" position and the wipers parked:

Notice how the parking system works. When the wiper switch is in the "Off" position, the orange/green wire is connected by the wiper switch to the orange/blue wire into the motor which is the low speed motor supply. When the wipers are in the parked position the parking switch within the motor connects the orange/green wire to ground, shorting out the motor via the wiper switch and stopping it dead. When the wipers are away from the parked position the parking switch within the motor connects the orange/green wire to the orange wire which is the fused power supply. This powers the low speed supply to the motor to keep them moving until they reach the parked position.

To wire in a flick-wipe switch, we need to be able to convince the motor that it is no longer parked. We can't just power up the orange/blue wire to drive the motor as that is shorted to ground via the wiper switch, the orange/green wire and the parking switch, so trying to power it will just blow a fuse. We need to wire in a changeover switch the overrides the parking switch. One way of doing this is shown below:

Use a momentary switch with three terminals. It is important that the switch is of the "break before make" variety, i.e. that as the switch changes over the two outer terminals are not both connected at the same time (in a "make before break" switch they will be and this will also short the power supply and blow the fuse). I believe that the standard Caterham Flash Switch should be suitable (but I haven't test it) and this will match the design of the other switches in the car.

To wire the flick-switch like this, cut the orange/green wire and connect via the switch as shown, with the (usually central) common terminal connected to the wiper switch side and the normally closed terminal connected to the motor side. Then join another wire onto the orange (fused supply) wire and take it to the normally closed terminal of the switch.

When the flick-wipe switch is in its resting position, the cut orange/green wire is reconnected and the circuit is exactly as before. When the switch is operated, the motor is disconnected from the short to earth through the park switch and temporarily powered from the orange wire. Once the wipers start to move, the park switch changes over and the flick-wipe switch can be released.

Wiring the flick-wipe switch above is convenient as the various wires can connected close to the existing wiper switch, keeping the wiring short and neat. However, some cars have an electronic intermittent wiper controller box installed that activates intermittent wipe mode when the wiper switch is briefly switched to slow speed and of again. Where installed, the wiper controller is connected between the plug and socket shown in the middle of the above diagram. The two connectors are unplugged from each other and connected to the wiper controller. It detects the short pulse on the orange/blue wire and will also therefore be triggered by the flick-wipe switch if wired as show above. I think the solution to this where an intermittent wiper controller is installed is to make exactly the same wiring changes, but on the motor side of the controller connectors as shown below:

Note that I haven't actually tested the above, but the wiper controller unit doesn't make a connection to the orange/green wire on the switch side, instead controlling the orange/blue wire directly. There will therefore be no pulse seen by the controller on the orange/blue wire when the flick-wipe switch is operated and I don't believe it will therefore be triggered into intermittent wipe mode. However, whether it responds as expected to seeing the motor coming off park would need to be tested. I think it will work OK. There are actually two different intermittent wiper control units, the Lucas 6DA as used on the classic Mini and various Triumph cars and a Caterham/Technisol unit which works in the basically same way, but may or may not respond in the same way to the changed wiring above.

The other alternative, if the flick-wipe switch is to replace the existing intermittent wipe function, is to remove the two connectors from the intermittent wipe controller and plug them together, taking it out of the circuit. The first proposed wiring diagram could then be used.

One other potential problem with this could be that as the flick-wipe switch returns to its resting position, the wiper motor is very briefly disconnected. Most switches snap from one position to the other very quickly and this would not be noticeable. If using a vintage Lucas type switch, sometimes they do not snap quickly from one position to the others and the wipers may stutter slightly as the switch is released. If this is seen as a problem, the flick-wipe changeover switch shown in either of the above diagrams could be replaced with a simple momentary switch and a relay as shown below:

Replace this (Switch Only):

With this (Switch & Relay):

The contacts within the relay will always change over very rapidly and any stuttering of the wiper motor as the flick-wipe switch is released will be eliminated. This also has the added advantage that a simple push button switch could be used, or a two pin toggle switch as the switch itself does not need to provide changeover functionality.

One final idea; there is a way of trying out any of the above combinations without cutting any of the existing wiring. Holden Classics sell complete sets of the 5-Way Harness Connectors used for the intermittent wiper controller. If you made up a small loom as shown below, you could simply plug this in line between the existing connectors or on either side of the intermittent wiper controller if installed and test before making any permanent changes to the car. The orange wires could be neatly joined in this case by crimping both wires into on terminal pin of one of the connectors. The connector shown with solid terminals is the connector with solid male pins, the connector shown with hollow terminals is the connector with hollow female sockets. The position of each wire in the connector may be copied from the existing connectors:

A similar loom could be made using the relay if required.

Hope that helps, let us know how you get on.

Andrew

[JNC]

Very nice work, It must have taken you some time to do all this thank you. I hope to have some spare time at w/e to have a look. The switch arrived today.   

[JNC]

I spent some time in the garage today and have fitted the intermittent flick switch with success, I bought a headlight flash switch from CC so it matched the other switches with three terminals and wired it as Andrews diagram, I did not use a relay.   

[revilla]

Excellent. Glad it all works :)

[Dave Hardcastle]

Another successful installation here

If only I'd found this before I blew an untold number of fuses and ruined my wiper motor park switch! Still, all's well that ends well.

Thank you for a great article. This ought to be in the guides section.

[revilla]

 

[JNC]

   

[rhauri]

You say you ruined your wiper motor park switch, what was the symptom of this?

Anything like the below at all?

• Wiper switch set to off
• Switch the car on
• No wiper activity
• Switch wipers on
• Wipers start
• Switch wipers off
• Wipers continue (and do not stop)
• Wipers only stop when the car is switched off completely and restarted

[Dave Hardcastle]

When the wipers are on, they stop as soon as you turn the switch off, rather than returning to the parked position.

Your symptoms sound more like the wiper switch needs replacing or a short somewhere.

If you have a multi-meter, use the diagrams in this thread to check what feeds/earths you have when you first switch on, then check again when the wipers are misbehaving. If you don't have a meter, for the cost and ease, I'd start by replacing the wiper switch.

Hope that helps,

[rhauri]

Cool - thanks Dave, that makes sense.

I don't have a multi meter, but I think I should invest in one.

I belive the switch has already been replaced as it looks brand new compared to the rest of the switches (sun faded), but still worth changing it out.

I have an inkling that it could be the intermittent wipe "black box", if I have one, so will be looking at that too.

For future reference though, where is the park motor switch and what does it look like?

Thanks again!

[Dave Hardcastle]

No problem, it's nice to put back in, if you know what I mean.

The park switch is attached to the wiper motor on mine, and those discussed in this thread. It is affixed to the motor via a spring clip, and the wires to the motor are attached to it. The motor is a right pig to get at though, on my S3. I don't have intermittent so can't assist with that.

If your switch has been replaced it may be worth checking that all the wires are properly connected, without any strands sticking out and shorting across terminals, just a thought.

[Jonathan Kay]

I don't have a multi meter, but I think I should invest in one.

Current recommendation: Draper 60792. It's worth getting some croc clips as well.

Jonathan

[rhauri]

Another good shout Dave.

I'll have a thorough look at it over the weekend - fingers crossed I find something.

Thanks Jonathan - Looks reasonably priced also.