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 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
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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.
Last edited by klhansen; Wed Apr 08 2020 08:18 PM.
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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.
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.
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!