Replace wiper switch with relay??

[TimS]

I've been searching for a while and maybe someone can help me get my thoughts straight...

I'm looking to replace my wiper switch with a relay. The purpose of this is so I can use a single throw switch for continuous use, and to have a momentary button on the steering wheel for a quick wipe.

Does anyone have a good diagram for a wiper relay to single speed VW wiper motor or an example of a relay that would work?

I have a single speed early motor that has been converted to 12v.

Thanks.

-Tim

[Steve Arndt]

There is a bunch of info on the samba about this. As I recall there is part of the motor and winding that powers the wipers into park position. Without that you can't make them park at the bottom. They coast to park then the motor grounds out to stall it at park (if I remember right, dad has all this memorized).

[Steve Arndt]

But later model super beetles and all golfs with the intermittent wiper feature have the single swipe feature which is relay based.

I have a vanagon wiper relay you can have for free to play with. I replaced it on my syncro with a later model passat relay which gave me infinitely adjustable intermittent wiper delay.

[TimS]

Let me check to see if I can get a late model relay cheaper than shipping, then I'll let you know. Thanks. I'll also look into late model beetle wiring diagrams... Good thought.

[TimS]

Okay, does this look like it would work? A DPDT relay?? Seems too simple compared to last time I tried to figure it out.

[Marc]

VW wipers use "dynamic braking" whereby the motor winding is grounded when the switch is off and the internal cam reaches the park position. Without dynamic braking, the wipers tend to coast through the park position (on a wet windshield, anyway) which makes it impossible to turn them off unless you grab the arm or turn the ignition switch off at the right moment...this is the basic reason why it seems so complicated to re-engineer the control circuitry. But wiper-delay control boxes that mount under the dash have been available since the 1960's, if your F.L.A.P.S. doesn't carry them you should be able to find one at a place like J.C.Whitney. To be compatible with dynamic breaking, each time you want a single sweep the ground path must be opened before power is applied to the winding - if a simple relay without any sequencing is used, there's a high probability of a momentary direct short occurring every time you hit the switch. Referring to your DPDT diagram, that would occur if the T2 contact to 4 doesn't open before T1 closes to 1. It'll probably be too brief to blow the fuse, but the contacts in the relay will be abused. I suppose that if you were to use two relays and put a choke in the control wire for the N.O. one its action could be delayed enough to remove this concern, but it's still an inelegant design since a failure of the first relay would guarantee a blown fuse.

http://www.shoptalkforums.com/viewtopic ... 8&t=100393.

The most elegant solution I know of is the Cole-Hersee switch that Chris V discovered. It has two speeds plus a single intermittent sweep that's adjustable at the knob (no need to "train it" every time you want to change the interval like you have to do with the VW relay-based setup). And when you press the knob, it powers an electric washer pump. Press it when "off" and the washer squirts plus you get several sweeps automatically. The only downside is that it's rather bulky and requires notching of the airbox.

Prior to `72, the wiper switch was mounted on the dash. When it was relocated to the steering column the park circuit wiring was rearranged to that of the waterpumpers, allowing the use of their relay (it can be added to any `72-up car; there's a stop in the switch which blocks its "down" position, easy to remove).

The round `70/`71 motors are the same as the `72-up internally but the control wiring must be altered to interchange them. The dash-mounted switch is incompatible with the late style park circuitry.

`67-`69 "square" wiper motors are electrically the same as the `70/`71 round ones, so the Cole-Hersee switch wires in like this for those. You'll note that Term 31b isn't connected - that's because the dynamic braking function is handled internally by the switch:



I haven't actually installed the Cole-Hersee switch in a `72-up car, but it should work like this:

[TimS]

Thanks for that very complete answer. I will read through it again and follow links tonight. I do understand your reasoning against the simple dpdt relay.

[TimS]

Okay, I researched that switch, and, although it seems like a nice delay wiper switch, I don't think it will work for my steering wheel momentary switch activation. My motivation is that when I'm driving through a puddle, I want both hands on the wheel and still be able to switch on the wipers. I don't have power steering, so unless I can preemptively turn on the wipers, the forces on the wheel can be too much for single handed operation. There are times when puddles sneak up on me.

I think I may give the DPDT relay a go and see what happens. In looking at online pictures of the inards of these relays, it looks like the vast majority of them run a single coil with the switching parts joined on a single hinge plate. There also seems to be a fairly good gap between the contacts. With the single hinge plate and significant gap, I think the risk of not switching simutaneously would be low. There are some DPDT relays that have two coils, similar to two SPDT relays, I will avoid those.

I'll post my results, yet it will be a while before I know. Thanks for the input.

[Marc]

...My motivation is that when I'm driving through a puddle, I want both hands on the wheel and still be able to switch on the wipers...

Hmmm. I hadn't considered that to be of vital importance, but if you do (and a left-foot-operated button wouldn't help) here's something else to consider. On the `72-up cars with the column-mounted wiper/washer switch it's a fairly simple matter to take out the leak-prone air valve for the washer and replace it with a microswitch to operate a relay for an electric washer pump...perhaps you could make that modification and use the lever to trigger your momentary-wipe system, it should be at least as easy to tug on the stalk (like a flappy-paddle upshift) while steering as it would be to fiddle with the extra switch position of the "stock" intermittent wiper arrangement.

You'd then have to come up with another way of operating the washer, but if it would be acceptable to take a hand off the wheel for that it shouldn't be hard. I had a daily driver with dash-mounted wiper switch in which I installed an electric washer pump - I modified an early push-to-test brake warning lamp in the center of the dash to trigger the washer pump relay. I liked it so much that I did the same thing to one of my race cars...on it I also used the existing lamp as an ignition pilot, which gave me a lighted target which I could see in my peripheral vision when I needed to hit the washers.

viewtopic.php?f=18&t=116431

Chris V's microswitch conversion for `72-up wiper/washer switch (first photo shows stock valve, second shows microswitch installed in its place):
http://img.photobucket.com/albums/v212/ ... 130096.jpg
http://img.photobucket.com/albums/v212/ ... 130095.jpg
He was truly stealthy and even left the stock hoses in place, running the wires to the microswitch through them - so the conversion is undetectable from inside the car:)

[richard123vmt]

My 71 vw bus came with pressurized windshield fluid. I removed the valve replacing it with a switch which I JB Welded on. The same push button and stalk operate the switch which then operates a pump and reservoir taken from a different car. It worked fine. I haven't tried it in literally years. I'm not sure it is all still there. But I did put on some new wipers recently.