Alan's Heated Windshield
Wipers Control Switch
Heated wiper timer switch
I wanted a better way to control my heated wipers rather than a simple toggle
switch. With the toggle it was easy to forget them on, long after the icing
was gone.
What I was after was:
(1) A way to turn them on
(2) Be able to turn them off manually
(3) Have them turn off when the ignition was turned off
(4) Have them stay off when the ignition was turned back on
(5) Have an automatic function to shut them off after a period of time
Chrysler minivans use a switch that does all of the above, but it was going to
be hell to mount one in a non-stock application. The switch enclosure is quite
large and is all one unit, so everything had to be mounted within reach. Not
much room in the typical dash for something that size.
With a lot of help from an electronics literate buddy we came up with a small
PC board and the right components to do everything I wanted. The module can be
remote mounted so all that has to go in the dash is a SPDT switch and a couple
indicator LEDs.
From left to right, the Chrysler switch, the guts of the new switch, the
box the new switch will fit in. The cigarette package is there to get an idea
of the size.

Here's the part that does the work. The blue cube is a 10 amp relay that feeds
current to the wipers. The blue tube above that is a capacitor which, combined
with a resistor, sets the time the circuit is turned on. After a couple tries
we got it to stay on for 17 minutes. All that goes from here to the dash is a
tiny, four conductor cable carrying a ground, a trigger leg, reset leg and
power to an LED pilot light. The light blue wires are power in (at top, with
black stripe) and output to the wipers.

It has to be manually triggered for each cycle. The time just
happened to come out to around 17 minutes, by playing with the
resistor/capacitor combination you can (supposedly) get anywhere from
milliseconds to hours out of the same design and timer chip.
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7-13-05
All photos and text ©2003 Alan Nadeau, All
rights reserved. Used with Permission.