The Stovebolt Site Forums The Shop Area The Electrical Bay Intermittent windshield wipers...

I'm in the process of designing/building an intermittent wiper appliance for the AD trucks. Originally I hoped to make the intermittent feature infinitely adjustable (and I have completed a working circuit with that feature), however I've decided that style will be too distracting, too fiddly and just too dangerous to be good for these trucks. Therefore I've decided on using an 8 position rotary switch and pre-set intermittent speeds. This is to be used as an addition to the electric wiper conversion kits for the AD truck commonly sold on eBay, Amazon, etc. And I think you could easily combine this with a wiper conversion for any other vehicle. These wiper motors (from what I've seen) are all the same. They're built with a two-speed self-parking motor. My scheme will as I said use a rotary switch with selections of: off, low, high, intermittent 1, 2, 3, 4, 5. Intermittent speeds will utilize the low speed motor option. Delays will probably be something like 1.5 sec, 3 sec, 5 sec, 7 sec and either 9, 10 or 11 sec. I'm happy to share the circuit or if it ends up being simple enough that I could make several at one time, possibly I could do that or just make it in kit form and let the user build it. I can tell you it will be a rather simple and reliable circuit feeding into a common automotive relay. My plan is to use the standard dash hole and the standard-looking knob. Alternatively I could have only 4 intermittent speeds and utilize a backward-rotating switch pole for a washer combined with straight low speed...although I doubt many of us have windshield washers. Thoughts? Ideas? Interest in this?

I added an optional (OEM) intermittent switch to my beer (read it upsidedown) and am much happier with it.

Instead of re-inventing the switch, would it be possible to use an existing switch from a newer model truck?

Only a very few switches include intermittent circuitry. Over the last 15 or 20 years, intermittent pulses have become a black box function (far cheaper to incorporate the circuitry into proprietary IC chips and let the switch operate simply as a selector). Some makers will add the delay box in with the relays, but you'd need their switch to make it work...($$$). Which switch did you use?

Since posting I've calculated/tested the values and I've settled on the following time delays: 2 sec, 3.8 sec, 6 sec, 8.5 sec

I believe the 8 position switch and the relay will be the most expensive parts. The switch seems like about a $7 item and the relay about a $2.50 item. There will be 9 resistors, 1 capacitor, 2 transistors, 1 rectifier and a circuit board...all parts together $30 or so (less if I order more to cut the shipping cost per each one built or drive out to Mouser to pick up the items). That all depends on how many (if any) people are interested.

My jeep was plug and play, so it was real easy to install. I'd be interested in something for my burb down the road.

Cool idea. For the time being (and since I'm not even on the road yet with my '51), I'm going to stick with vacuum wipers. But I'd be interested in the circuit diagram and components. Controls are something I've always been interested in, even though I'm a Mechanical Engineer.

Back in '84 I bought an F250 that didn't come with intermittent wipers. I just bought a different switch and stuck it in and 'voila', had intermittent wipers. Everything was built into the switch. Like you say, nowadays, this is done by black boxes. Opening those up just makes me go "HUH??"

The first schematic I've drawn is attached Kevin. There are a couple of resistor values I'm still playing with, I'm considering using slightly different transistors (these are 2 very common general application types which might or might not be responsive enough) and I don't have the 8 position rotary switch yet but here's how it works:

12v + comes in from the wiper switch (via the low speed lug). Ground provides the 12v - for the control. If the rotary switch is set to the 1st position, the 12 volts runs straight through to the low speed circuit of the wiper motor and runs as normal. If the switch is set to the 2nd position, the 12 volts runs through to the high speed circuit of the motor and runs as normal. If the switch is set to the third position, then some resistance/capacitance magic occurs, a couple of transistors get to flip and flop and do their thing and then the 12 volts runs through the normally open contacts of the relay to the low speed circuit of the motor as a pulse when the contacts of the relay close. Running through the 33k resistor, the pulse rate is once every 2 seconds. Running through the 75k resistor, the rate is once every 3.8 seconds. Running through the 120k resistor, the rate is once every 6 seconds and running through the 180k resistor, the rate is once every 8.5 seconds. When the wiper motor senses there's no current, it goes to park and waits. Part of my curiosity at this point is "does the 2 second sweep give the motor enough time to park and wait, or is that too fast for this motor?" Once I finish building it, we'll see. There's in my mind the possibility I might have to make 3.8 seconds my fastest speed and add an option for 10 seconds or so.

On my truck and some of the other stuff I own several items work intermittently, I didn't know that someone had spent time makin' them that way. If you need any help I can point out some special substances like oxides that seem to promote the behavior.

Jon
The only comment I might have is to rearrange the switch functions so you don't have to go to high to get to intermittent. Just a minor thing.
Good work.

Thanks Kevin,
I thought about that also. What sort of led me the other way was that I figure the low and high functions might be used more often so I wanted them to the the first things a person would get. And additionally, the rotary switch will make a full circle so you could go back to off either by turning back from low/high or clockwise from intermittent. I'll give it some more thought, however. The way I made the circuit that would be an easy change. Part of me wonders if the intermittent function might not be used more. I don't get the feeling too many people drive in the rain...intentionally.

At least not in their stovebolts.

While on the topic , whats involved in turning a single speed wiper into a two speed ???

John

That is a good question, John. If you mean can you make a single speed motor run faster, the answer is not without ruining it and usually ruining it spectacularly. A two speed motor will have 2 distinct coils inside...there will be a low speed coil and a high speed coil. It has to do with different magnetic fields produced when each coil is energized. If you have a single speed motor you want to slow down, it is possible to produce a voltage-reducing circuit (or to simply use a 12 to 6 volt resistance mechanism) which will just give the motor 1/2 of the voltage for which it was designed. Then the motor will run at half speed but it is important to understand you will probably also lose the torque produced by the higher voltage and it is likely your motor will run too hot.

The tricky part is: If you limit the motor to 6 volts, it will run but it will it try to draw the necessary amount of current (please remember voltage and current are different...voltage may be thought of as the size of your arm while current may be thought of as how strong your arm is). That amount of current probably won't be available. In fact, you'll need twice the current at 6 volts...but that's another discussion. If you run the motor using a 6v reducer, run it for a while and keep your hand on it. If it feels hot, then this approach won't work. Most 6 volt motors will run just fine with a voltage reducer, but most auto motors are fan motors, etc which don't need much torque. The wiper motor is more like a starter motor in that it produces a decent bit of torque (which is then geared down further). And when the wiper motor starts, it sucks more amperage than you'd expect...most are fused at 20 amps. In a perfect world, you'd turn your motor into one with two separate coil windings. Hope this helps.

I was hoping to slow it down as it one speed and that's fast. I guess I should search out a 2 speed motor as well as a switch, the higher end trucks must have had them .

Thanks
John

I assumed you were using 12v as there weren't very many 6v wiper motors out there. What truck do you have, John? If I had some particulars possibly I could offer some help.

On the rotary switch placement, I've decided one logical array would be "off" at the straight up position. Normal low and normal high clockwise from that. Relay selections counterclockwise with 2 sec first, 3.8 sec next, 6 sec next and 8.5 sec next.

I've ordered the materials to make a few of these. No idea when they'll arrive, but I'll keep you posted.

Right Jon G I should have mentioned that . 62 chev c 30 about as basic a truck as they came. For washers I will use a rubber diaphragm pump on the floor with a bag or bottle under the hood.

John

John as I recall the 1962 sort of sat out there by itself on some things...possibly the wiper motor also. But the more I think about it, there was a dual speed motor used very commonly in GM passenger cars from 1957 through the mid-60s and I'll bet one of those or a new replacement of it could be adapted to work in your truck.

Hi Jon G.

Very cool idea. I like your circuit design.

As you probably already know, the wiper switch sequence on most production GM vehicles with the delayed wiper feature goes from off, to max delay to min delay, to lo speed, then high speed. And yes, like many other features, wiper function on new vehicles is typically up-integrated into some type of body control module. This provides for better control, more flexibility in switch design (switch is now just a low current input), expanded features like wipe for n number of wipes whenever the washer is activated, and easier integration of automatic controls such as rain sense or headlight activation whenever wipers are on.

With regards to wiper park, the vehicles you are designing for may be different, but the GM wiper motors that I am familiar with typically have 12 volt ignition going to the motor, with the wiper switch controlling the ground path to either the low speed or high speed motor windings. The motor typically contains some type of cam and switch arrangement, which provides an internal ground to the low speed motor winding until the wiper arms reach the park position. There are those on this forum that know these circuits well, so I'm sure they will correct me if this is in error.

Hopefully I'm wrong, so you won't have to modify your circuit - as it controls through the high side. Speaking of which, if it does drive thru the high side, will that 10K resistor in series with the rotary switch cause an issue ?

Also, I confess that I'm trying to figure out how the rest of the circuit works. I get the part about the NPN transistor energizing the relay. I also (I think) understand that you are changing the RC time constant of the circuit made up by the cap and whichever resistor is selected from the switch. I see that you have the negative plate of the cap connected to the emitter of the NPN. Is that to discharge it whenever the relay is energized? Also, is it possible that the collector and base labels on the PNP transistor are reversed? I'm thinking that the maybe RC should be attached to the base?

Sorry if these sound like ignorant questions. The last analog circuits class I had was in like 1986.

Best Regards...

p.s. I've seen a lot of these circuits designed with 555 timers. Would that be an option, too ?

p.p.s. My truck has vacuum wipers also, so when you come up with a design to add the delay feature to those, let me know...

It's under the center of the dash, but not to hard to get to. I had a 61 biscayne at one point with 2 speed wipers , I'll have to search the wreckers for what I want , maybe even Carlisle if it happens this year .

John

Hi Bob,
Thanks for your thoughts and questions. This controller was designed to use only a wee bit of juice in the circuit itself. I'm aware of the two wiper motor designs...to power or to ground. In this case, I don't believe it will matter since the relay operates just as a switch would. I've tried the motor and touching the correct wire to 12v + with the same approximate speed of the relay switch causes it to go through one motion cycle and park without issue. So at this point the only question remaining is will the 2 sec delay give enough time. Said a different way "will the 2 sec delay send another pulse to the motor before it completes the sweep?" Because that won't be the best plan. If not, adjusting will be easy. In fact I originally thought of using 4 tiny variable resistors which could each be adjusted as desired...but I didn't have them and thought it might be over-complicating without need.

Yes, I think most switches work that way. In this case the switch will be sitting on top of the dash, however. I can of course wire it any way at all...I'm just thinking of what will be the easiest and most logical to use. Probably just a matter of getting used to it. I doubt many owners of these trucks would be letting other people drive them in the rain. Maybe we should take a switch position poll?

As for the circuit, yes...you're on the right track. It is the simplest RC circuit I could think of...cobbled mostly from a light sensitive circuit I created around the same time you were taking your last circuits class. Did I flip the base/collector/emitter? I've been known to do that and I'll tell you the two transistors I had here...one was different. One was CBE and the other was EBC in orientation. I'm not looking at the schematic now but I will later today. The original diagram was drawn hastily, modified as resistance values needed to be changed and then cleaned up a bit. If I made a mistake, that's when it happened. The 10k resistor was put in there to add a bit more resistance before the switch started selecting individual resistors. This is a way of saying it helped make the after-switch resistance values closer to what I needed plus it seemed to me if I needed to adjust upward the time delay of one speed, I'd need to adjust upward the delay time of all of them and using a single resistor before the switch would be the easy answer. Hopefully that makes sense. Once I receive the switch I've ordered I'll be able to hook this all up and try it. Right now it is working with a single resistor and seems to be spot-on.

I considered using the 555 IC and that would work fine, but I'd still have to have a selector switch, different resistor values, etc. Plus I didn't have one handy the afternoon I started working on this.

Intermittent vacuum wipers? Don't you just step on the gas pedal for that, Bob?

Hi Jon G,

Thanks for your reply, and good luck with your project!

You are right about stepping on the pedal. Fortunately I don't drive too much in the rain.

Best Regards...

Well Bob,
Thanks! After a nice day out in heat/humidity staining the fence I decided to see what the delay circuit would do when connected to the wiper motor...and I'm confused as to the park circuit. It (the P connection) has 12v + when the ignition is on and also when the motor is running at high or low speed. I was thinking the relay sending 12v+ to the low speed winding would be sufficient, however the wiper motor moves only a bit at a time and doesn't park. Yet when the switch is flicked rapidly to low speed and back to off, the wiper motor makes a full sweep and parks. Ideas? A pulse stretcher?

Hi Jon,

Plz ship some of that warm weather up our way. It is still pretty cool up here.

Is the motor that you are using connected like the one shown in the diagram on this page ?

Wiper Schematic

This type, with the ground circuits used to control operation, is the type that I am familiar with.

Bob

My vacuum wipers work intermittently. You can set the pause with your right foot on the gas 🤣

Would that technique work on 6v and 12v systems (positive and negative ground)?

Thanks

Hi Bob, no...this is a new motor and not one of the GM ones. This is the type sold on eBay, Amazon and elsewhere and looks like this: https://tinyurl.com/t4z65t3

4 wire switch: power, low speed, high speed, park. Park is disabled when the wipers are working and enabled when the wipers are switched off. That's the part I missed earlier...and 20 or 30 years ago something like that wouldn't have gotten past me.

Before going to sleep last night, I had the idea that the answer might lie in 2 relays. I know...that sounds strange, but I think it might be the answer. One to energize the motor winding (a normally open relay which is closed by the intermittent circuit) and the other to disable the park circuit (a normally closed relay which opens for the intermittent controller's pulse and then closes). I'm going to try that idea later today or tonight.

If I remember correctly those type motors park circuit only work with the right type of switch that puts power to the park wire only in the off position. Then a switch internal to the motor assembly opens when the motor gets to the park position. So ya you'll need to make sure that park circuit stays dead when your in the intermitent mode. Years and years ago I put a universal intermitent kit into an F100 I had. If I remember it was a little box with a pot knob that hooked between the trucks wiper switch low speed wire and the motor. You'd switch into low then adjust the speed with the knob from full normal to one swipe every 15 seconds or so. It was a cheap pos that only lasted a couple of months before it stopped working and I had to rip it out in order to get the low speed working again. Good luck with your project it sounds interesting, keep us posted.
Dave

Jon

I think you're right about needing two relays. I looked at the wiring diagram for a modern wiper motor with intermittent and it has a park relay. Not need without intermittent, as the OFF position energizes the park circuit, which then opens a switch inside the motor when in park position.
I can send you a copy of that diagram if you'd like.
[on edit] attaching diagram.

Hi Jon,

OK. I see what type of motor you are using. I did not see a schematic anywhere on that link, but based on what you told me, it probably looks like the attached (Standard Wiper).

If this is correct, then it probably operates just like DaveMcK38 describes, when the wiper switch is turned to "Off", power is applied to the park circuit, and the motor stays energized until the wiper arms reach the park position, and the internal switch opens.

Been sitting here thinking for awhile, and I think you guys are correct about a second relay. Can't really come up with a solution without adding one.

One suggestion (other attachment) that might make your life easier, would be to use a double throw relay - like in the circuit provided by klhansen. If you had power on the relay common, you could connect the park circuit to the NC contact, and the low circuit to the NO contact. That way, your pulse circuit would only have to energize the relay long enough for the motor to move enough to close the park switch, and you could then just let the motor handle the rest of the wipe cycle.

The second relay comes into play in order to isolate those circuits under normal operation. I suppose you could also use a 2 pole selector switch that would do the same thing, but I know some of those can get rather expensive and kind of large in size.

klhansen,

That's an interesting circuit. It looks like the use the "Run Park" relay for motor activation, and the "High/Low" relay for speed control. The park switch looks like it has two jobs, one to keep the motor running until the wiper arms make it to the park position, and the other to signal the controller (GEM), that the motor is parked.

Best Regards...

Thanks very much Bob, Kevin, others,
I spent time last night studying all the parts, thinking as critically as I could and thinking about this whole she-bang from start to finish. There were some aspects I missed and now I believe I've sorted them. Sorry for any confusion. Another realization...this circuit is going to take 3 relays. Why 3? Two will be required for the delay circuit and one will be dedicated for the regular low/high function. The rotary switch contacts aren't rated highly enough for the wiper motor's current and while the park circuit relay can be shared with all functions, I think it will be easier to use another relay for low/high. Could I have just bought a heavy duty rotary switch? Yes, but the imported Bosch style relay is less than 1/10 of the cost of that switch. Hopefully tonight I'll have a working circuit incorporating everything. Thanks again!

Guys...I'm stumped. The delay circuit works fine, is infinitely adjustable but has distinct trouble with relays. I've tried using one relay to switch current to another relay. I've tried Bosch type relays by themselves. I've tried one Bosch type relay using both the NC and NO functions (which aside from the trouble with the relay signal from the delay circuit actually will work).

Here's the dilemma:
1. some relays (like the Bosch type) will pull down but only very briefly (fraction of a second)...not enough to make the motor start and to to the park circuit.
2. some relays (including the Bosch type) will pull down for an extended period of time but will not work (will only chatter) if the 12v time pulsed voltage is shared with the relay.
3. isolating the relays hasn't seemed to help. In fact, none of the isolation has seemed to help.

Using a relay to send current to a Bosch style relay which gets its switching voltage from a dedicated + wire will work...however only at a fairly fast intermittent rate. Otherwise it works but of course the wipers continue to work in low speed until the relay finally releases.

Ideas? Thoughts? Naturally the output voltage/current have to be strong enough. They're not at this point. I should also mention this isn't on a temp breadboard. I went ahead and soldered it all nicely so there'd be no loss due to temporary connections.

Maybe you need a double delay circuit that is on for a long enough period for the relay to pull in and power the motor and clear the park switch, then turn it off and wait your desired interval before activating again. How to do that is beyond me, though. Are there electronic relays that would work? Sorry I can't help more.

DigikeySome of these look like they'd interchange with Bosch relays

Thanks very much Kevin, I've thought of something along those lines, but the turn off/wait part isn't something I came up with yet. I did find a no/nc relay with contacts rated at 5 amps which works...up to a point. At any wipe speed less than about 7 or 8 seconds, the relay doesn't let go and the wipers continue to run as if on normal low speed. If you look at the circuit diagram and think of the adj resistor, it would be at about 60k ohms when the thing no longer works correctly. I'm certain I've read something about this, but right now I can't recall where nor what it was. Hopefully somebody will know what I'm talking about. Ideally I think the lowest wipe speed delay ought to be around 2 to 3 seconds. I have the longer delays whipped, though.

Oh all this work in a quiet garage has made me realize how noisy that add-on electric motor is. I'm also thinking of ways to make that a little more quiet. Mounting on the other side of the firewall would help, but I don't see that as a possibility.

Hi Jon,

If you get a chance, can you share your latest circuit and the relay PNs you are using? You can PM me and I will give you my email, if you don't wish to post it. Would be helpful to include any wire lengths and gauge sizes as well.

Without seeing the latest design, a couple of thoughts come to mind:

Are you experimenting on a bench with a power supply, or on an actual vehicle with a battery? Relay chatter can sometimes be caused by voltage fluctuations due to the high inrush current of a DC motor. (Relay energizes, motor activates, current spikes, voltage drops, relay deactivates, repeat...) Inrush can be much higher than running current, so a supply that would seem to provide enough current normally, may be temporarily dipping low enough to affect electronic circuits.

Also, and you probably checked this, but are you sure that the transistor that switches the relay is fully into saturation? Without going downstairs, and blowing the dust and spider webs off my circuit design books, I seem to recall that when used as a switch, the rule of thumb for bipolar transistors was to run base current 10 times normal saturation to ensure that it stays out of the linear region, and does not fall back into cutoff. Perhaps you could try reducing the value of the 3.3K resistor that feeds the 4401 base? Maybe clip like a 500 ohm or 1 K across it ?

I remember building basic automotive relay drive circuits in the past for quick tests. In order to drive the relay coil I sometimes used a TIP 121/122. It is a Darlington design, so it has tons of beta, and can drive up to 5 amps.

TIP

I used to also sometimes drive relays using the parallel port from a PC. (This was wayyyyyy before USB) To electrically isolate the PC from whatever it was we were testing, I used optically coupled relay drivers something like these.

Opto Isolator

They also have really good beta (transfer ratio, technically), and can easily drive an automotive type relay.

Lastly, do you have access to a scope? It would prove very helpful in debugging transient conditions like this.

Best Regards....

Hi Bob,
Thanks...please check your PM for my email address. I'll post this here in case anyone else is interested. Last night I was thinking about an opto isolator, but the only ones I have are limited to 1 or 1.5v. I have some Darlingtons I''ve used in alarm circuits 20 years ago. I have the 122 and the 127 plus the 5305. Thanks for mentioning those. I hadn't thought about them yet.

The circuit hasn't changed from before. I've been waiting to post it here, and I will once I know it works. I've tried tweaking certain aspects (resistor & capacitor values & relays, etc). First I set everything up on an old plug-in board, got it working (still have that temporary circuit here) and then built on a small (2 x 2) perfboard using the same size wire that's on the resistors, transistors, capacitor for connection. I've tested inside with a smooth power supply and on the vehicle. I've used 16 or 14 ga wire when testing on the vehicle and indoors alligator clip common patch cords.

Base-emitter saturation voltage is a min of .75 and max of 1.20 volts. Good point about the 3.3k resistor. That value was actually a stab in the dark and I've left it alone, but it might need to be a bit less. Yesterday I even dug out a box containing some old circuits I've saved to see if anything came to me...without success.

I don't have access to a scope. Not anymore, anyhow.

The relay came from a box of stuff I've saved since the early 70s. It is an NEC MR301-9ES. I don't think it has been made for a long time. All I know about it is that the contacts are suitable...rated at 5 amp at 16v and the wiper motor draws 2.6 amp on startup. It is NO/NC and the coil is around 250 ohm. This isn't one of the dual relays NEC sold back then, though. I've tried others. I've tried using a common reed relay to switch the Bosch type (and this works up to a point). It had been my hope to be able to use the Bosch type relays, however the problem is that they switch off too rapidly. This is to say they don't stay pulled in long enough and the low circuit doesn't move far enough or long enough to do anything but oooch the wiper blade forward a tiny bit at a time and without enough movement to kick the park function into play. The Bosch type relays have contacts rated to 30 amps at 14v dc, max switching power is 560W, the coil resistance is 70~80 ohm, coil operating current is 160ma, pulls in at 8v but drops out somewhere between 1.2 and around 5v.

Hope this is helpful.

Finally (after 3 weeks of fiddling with this) I along with help from Crowbar Bob have figured out the problem and settled the circuit's issues. Bob discovered another gentleman had posted this same circuit on the Stovebolt site some time ago. And I discovered it also posted by a man in Canada who was trying to add intermittent wipers to his Volvo. The Canadian fellow said the circuit sort of worked for him but had problems. I'm pretty sure I know what he meant. This was a very popular circuit shared far and wide in the 1970s and I've used it or variants of it for a few different things since I first saw it...but for intermittent wipers using one of the popular "drop-in" electric wiper conversion kits it simply will not work. Not without a couple of changes anyhow. The good news is I now have 4 intermittent speeds, regular low and regular high. The better news is I can use one single inexpensive imported Bosch-style relay and mount it on the firewall or somewhere outside the cab where it won't be clicking when the wipers are in intermittent mode. When I have time to draw a new circuit schematic, I'll post it.

They offer an intermittent switch for my wiper conversion but it won't fit in the stock location so I opted out on the switch.

Here is the circuit. If anyone wants to tidy this up using one of the schematic programs, please feel free. I don't have one, so I just draw mine. Also as you can see in the attached digital image, this circuit can be notably miniaturized. The capacitor I had was a 25v (which is a larger case than a 16v). I think I could set it up in at least half the space on the little board I had (2" x 2.25"). I plan on nesting the 4 resistors on the back side of the rotary switch, and I think there'll be plenty of room. The relays (2...one for all the delay functions and the slow speed function and one for the high speed function) will be mounted somewhere on the firewall or in the engine compartment.

I set this for 3 sec, 6 sec, 9 sec and 12 sec delays (roughly). Alternatively you could use variable resistors on the board and adjust each delay option to match what you want. And soon I'm going to add a wash/wipe function in case anyone wants to add a washer to their truck. That will be done with a separate push button switch.

I said I would post a wash & wipe circuit once I had time to create one. It is attached and I hope you like it. Actually I think you will. This like the intermittent circuit could be used in many different vehicles. It is designed using the NE555 chip and while it may look complex, it really isn't. In fact, if you're interested in electronics or if you know a little and want to learn more, I believe buying a book on the 555 chip would be a good thing to do. This chip was created nearly 50 years ago and I'll bet there are several of them in your family car, your tv, radio, etc.

This particular siamesed circuit has been designed to work from the input of a single push-button switch. If you press the switch momentarily, the wash and wipe actions will begin simultaneously. Then in apx 15 seconds, the washing will stop and in another 4 seconds (probably 2 sweeps of your wiper motor) the wiping action will stop and the wipers will park. A couple of notes: you will run the wipe portion of this circuit to the same relay which serves the intermittent/low speed function for the wipe function. You'll be wiping at low speed. You'll need another Bosch style relay for the wash action since it is an action separate from the wiping, however it is possible the output from the 555 chip might just be high enough to power the wash motor...but I rather doubt it. The timing was a choice on my part. You could substitute the 1meg and 100k resistors for variable resistors and adjust the circuit to suit your taste. 15 seconds (plus 4 for a couple of clean-up wipes) seemed like a pretty good amount of time and I wanted something that would be simply one push of a button...which could be hidden under the dash or possibly on the side of the steering column or on your directional signal housing. Oh, one other important note: I set this up initially using 1N914 diodes. Please change that to 1N4002 diodes.

If questions, please let me know.