Attention Electrical Gurus, Need help with windshield washer wiring Options

[bbrock]

Right after ordering a complete Car Magic kit to convert my windshield washer to electric, I read Sir Andy's excellent tech article on the conversion. The idea of pulling power for the washer pump off the intermittent wiper feed so the washer is activated by pulling back on the wiper lever was too elegant not to try.

I happened to have this nifty vintage VW style splitter I bought some time ago for not other reason than I thought it might come in handy for some future custom wiring project. It was just the ticket for splitting off of my intermittent washer relay to power the washer pump.



After hooking everything up, I pulled back on the wiper lever and HUZZAH! The washers squirted and the wipers ran for two sweeps and parked. Pretty slick! I couldn't understand how the intermittent wipers would work when the lever was pulled down to turn the intermittent wipers on. I pull down on the lever to test them and nothing. As soon as I unplug the washer pump, the intermittent wipers start running. I'm not sure how the intermittent relay works, but thinking the timer is from charging a capacitor which then "bump starts" the wipers to run a single cycle.

Is there is a reasonably simple way to isolate the pump so it allows the intermittent mechanism to run without activating the washer pump? Could be a fun project. Or should I just go back to the original plan of installing the Car Magic switch? I just like the idea of minimizing the wiring.

[bbrock]

GENIUS!

Dug through my spares and found an unopened package of 1N4001 power diodes. Good for 50v and [EDIT: misread the data sheet. Only rated for 1 amp so I need to source a beefier diode, but the proof of concept is valid]30amps so plenty of head room. Vf is pretty high at 1.1v which is good for this application. Hooked one in series on the brwn/black wire and fired up the washer pump. Ran perfect. Pulled the lever down to turn on the intermittents and waited. No movement but a groan was heard from the motor, stopped, and repeated again after about 10 seconds. Hmm, sounded horrible but sounded like progress. I hooked up a second diode in series and WALLA! All functions are GO!

Should I add a third diode for an extra margin of isolation? So stoked! So the conversion now is down to:

- ~ $20 for a washer pump.
- A couple feet of wire
- 2-3 diodes
- (1) 3-way connector
- (1) 1/4" female spade crimp connector with locking tab
- (2) 1/4" female spade crimp connectors
- (1) ring connector (forgot the size I used)

Maybe $25 all in?

@lesorubcheek in my short remedial reading on diodes, I read that Schottky diodes have exceptionally low forward voltage so probably not the best choice. It seems cheap power diodes with high forward voltage are a better option.

Thank you, thank you for suggesting this. So simple and elegant. I'll use the LVD I ordered on my snow plow so it will go to good use. That was part of the calculation in ordering it.