The Stovebolt Site Forums The Shop Area The Electrical Bay Wiper Motor Switch

Hello All. I am rewiring the dash on my '58 4400. The original Wiper Motor switch crumbled in my hands while unplugging it. The Truck has a 2 speed electric Wiper Motor. I haven't been able to locate the original style switch, well one the a normal person can afford. Most of the vendors offer an aftermarket replacement, the details say that it cannot be used with the original Wiper Motor. My question is "Why"? Shouldn't I be able to adapt this switch to work as the original?

https://classicparts.com/1947-59-wi...ZGTyV7TnscT1S3YAuew3qRab4zeDsA5Ba-8_x6TU

I have that switch in my truck with an aftermarket wiper motor setup.

It applies power to each of the terminals in sequence as you turn the speed up.

I don't know about the original truck switch, but the original Corvette switches from the 60s grounded just the "low speed" pin on low and both the "low and high speed" pins on high.

Maybe that is what it needs? As I understand it, the goal was to have power always applied so that the park function would work without having to run an extra power wire.

Let me see if I can find a wiring diagram for the original electric wipers. That should show the switch and give us an idea what it is expecting.

This answer is GMC based, but I'd bet your life it is the same on Chevys. I'm pretty sure the electric wiper setup I put into my '57 GMC back in the 90s was from a TF Chevy.

The stock knob on the dashboard just moves a cable, as does the vacuum wiper knob. Unfortunately the two cables are not the same. The cable for the electric wipers operates two sets of contacts INSIDE the wiper motor assembly. You can find the GMC info starting on THIS page and continuing for 5 pages.

A guy that was the electrical equivalent of mechanical genius Hot Rod Lincoln could open up the electric wiper mechanism, remove the moving contact for high and low speed and wire the aftermarket switch in to replace them. I'd probably screw that job up and no longer have an operational electric wiper motor.

Bill, the switch on my '58 has 3 connections, 2 the from the switch to the Wiper Motor, 1 from the Ignition switch (12v power). There is a separate wire on the Motor connecting to a ground, no cable.

I don`t know anyone thats been able to get that switch offered to work.

I believe the original switch is grounded by it's mounting bolts. It has a metal housing. If that is what you have.
1. The switch has two wires.
2. The motor has three wires.
One motor wire is hot from a power source. (brown) (Keyed hot I think). The other two wires are Hi and Lo. (WHT and BLK). It seems that the original switch grounds those wires from the motor to it's housing and thru to the dash/chassis. For Hi or Lo. So the aftermarket switch may work. It is designed to have a hot lead to it and distribute power to it's other terminals for Hi or Lo. So instead of supplying power to it's hot terminal, you would ground that terminal. Then wire it's other terminals to the two motor wires. The third motor wire is wired to a hot souce as original.
Of course, any rotary switch with three terminals can be used if it shows continuity from one terminal to each of the other two, separately. I don't think you want a switch where terminals are all on or all off.

You can test your motor with key on, touch each of the two to ground, one at a time and see if you get a Hi and Lo speed. The two that you are testing are the ones that went to the original switch. The hot motor wire should still be wired to an original power source.

The 60-63 wiper switch is less expensive. It is a one speed.

Others can review, comment, refine.

Bart's description of the wiper motor operation sounds more like the 1960s (and maybe earlier and later) version of a GM 2 speed wiper system. Definitely not like the one in my 57 GMC (and that I linked to above).

He is correct when describing the switching operation where the switch just provides a ground for either the high speed or low speed motor circuit. Every time the wiper system gets back to "park" it opens a switch that provides ground for the motor. If the switch is in the "high" or "low" position, a ground is provided and the motor continues to run through another cycle. If the switch is in the "off" position (ie. neither "high" nor "low" providing a ground) the motor stops.

There are vacuum, electric and electric/cable. On the electric, when in off position, the motor rotates in the opposite direction until it gets to park position, and at the same time trips an actual off switch.
Vacuum and cable have their own ways of parking.

TUTS59: I pulled the data in my shop manual and FAM and it shows that the electic wiper should have an ignition switched power (brown) wire for the main power. There are two diagrams and one shows that as a 16GA and the other shows it as a 20GA.

None of the diagrams I have show the switch, but if you are up for a bit of experimentation, I suspect we can sort out what signals the wires need and figure out a switch solution for you based on that.

If it were mine, I would power the brown wire (+12) and try connecting each of the other two to ground.

If it runs at the two speeds with the two wires connected to ground, that will be simple to control with the switch you linked above.

If it runs a one speed with one wire grounded and not at all with the other, then I would try grounding both at the same time. If that makes it run at the other speed, we can still make the switch above work, but it will take a little more effort.

If neither of those does anything, you could try powering the two wires separately. I would be very surprised if that worked because that is the "normal" operation of that switch and anyone could have made that work.

On a related note, a picture of the crumbled switch might be helpful as well.

From what you and Bartamos have said I can pretty much plan my way forward.

The Wiper Motor does have a 20ga hot wire fed from the ignition switch. I assume that it grinds as you say back through the switch. I haven't been able to locate a diagram for the switch itself.

I was thinking like you that the aftermarket switch could be made to function. I'll run a few tests on the motor with power applied and see where that takes me.

Thanks for all insight Gents..

A few years ago I wrote a circuit for on/off, low, high and intermittent control of the aftermarket 2 speed electric motors used in all sorts of vehicles. I meant to offer it here but then Covid and other things got in the way. I ended up having to use 2 Bosch style relays to make it work correctly. I'm going to resurrect that work when it gets cooler. I used a 6 or 7 position rotary switch with it.

Be sure to have the case of the wiper motor grounded when you run your tests.

I've attached an explanation of how this type of wiper motor operates.

Craig, sounds like you have renewed vigor. Let us know if you have any troubles.

Bill thanks for the diagram. I may buy a cheap aftermarket switch and modify it to work.. More to follow.