I have 2 universal wiper motors that I have wired together They are wired as follows:
The negative terminal (-) goes to ground.
The positive terminal (+) goes to a fused power source.
The switched terminal (S) goes to one side of a toggle switch and to ground from the other terminal on the toggle switch.
This is not a "Mighty Wiper" brand as their wiring is not as above.
My problem is that when I start the wipers they work and if after a few seconds I shut them down they will shut down. However, if I leave them on for more than say, 20 seconds, and then shut them down, they won't. They keep on running. Sometimes (rarely) they will shut down, but more often than not they won't. I've been told that a diode is needed as there may be some feed back. There are no relays in the system and I don't want to rewire the whole system so that each wiper has it's own source. Each wiper comes from a common feed and each wiper comes from a common ground. Question.....what type and size of diode do I need and where does it go?