Thursday, October 30, 2008 Windshield Wiper Motor


Let's take a moment and reflect on the unappreciated windshield wiper motor. Great torque, dual windings, quiet operation for under $20 - this baby is made for Halloween. The wiper motor as removed from the car has a 'park' position that gives you a clunk every revolution. It is simple to open the case of the gear assembly and take out the cam that caused the thump. I mounted mine to a 3/4" plywood base that has proven handy for installing the motor to a variety of props. It also helps electrically isolate the motor case (DC ground) from any other AC prop accessories, such as the PC power supply below.

This is the schematic for the entire wiper/washer circuit in a GM vehicle. The wiper/washer switch is not part of the wiper motor assembly but is included because it identifies the function of timer and cycle switches built into the motor assembly. The only connections that I have used for props are the Purple (+12 volt for high speed), Yellow (+12 volt for low speed) and Black (12 volt chassis ground). These wires all come from a three-pin connector on the motor itself. Note that you would connect either the Purple wire or the Yellow wire to +12 volt, depending on your desired speed, but never both.


Scary Terry - Wiper Motor

Howstuffworks - Wipers

11 comments:

Allen said...

Adorable work!!!
what will happen if I connect it ton purpal and to yellow.Is their any difference??

Phil said...

The purple and yellow wires produce different speeds when connected individually. I haven't connected them simultaneously but suspect it would be bad...VERY bad.

CaffeineMan said...

I am looking into getting into this hobby. Last year a friend of mine in a crunch for time asked for my help with the PC power supply, this created an interest. I found your blog with the exact motor that I found for myself. I wish to use this motor to drive my first project. I will be using an older PC power supply. I would like to hook the yellow (or purple) and black wires up to the motor. I would like to know what pins to hook the power supply to. I reviewed your schematic and can not read it. I learn as I do, if this project goes well, I see more in my future. Thanks in advance.

Phil said...

Hey CaffeineMan - Are you looking for wiring information on the motor or power supply side?

CaffeineMan said...

Thanks for your quick reply. I will use http://www.letu.edu/people/joelkoblich/Tech_Tips/PC%20Power%20Supplies/Tips%20on%20Using%20a%20PC%20Power%20Supply%20for%20Projects.pdf and http://web2.murraystate.edu/andy.batts/ps/powersupply.htm to convert my PC supply to use. The motor I was going to hook the yellow wire 12v and the black common ground wires 3 and 10 if you use http://www.scary-terry.com/atxps/atxps.htm to the motor... but which wire to which connector?

CaffeineMan said...

Sorry for the double post but I did not think I was clear. What connections to the motor do I need to make? I know I need to hook into 2 of the 3 connections on the motor. The picture above looks like you have the yellow wire in the center, and the common ground on the top. I spoke to my buddy about the computer power supply, he said he did not try it because it would burned up after long continual use, have you seen this?

Phil said...

You are right that the order of pins in the connector is purple, yellow (center) and black. I have never had a wiper motor or power supply fail, though the longest continuous duration that I run them would be about six hours.

CaffeineMan said...

The power supply I was using was shot. I got a different one and it worked with the windshield wiper motor. I wish it was faster but this should be a good start. I was thinking of going to a thrift store and picking up a sewing machine and using the motor for multiple speeds. Have you ever use a sewing machine motor over a length of time?

Phil said...

I have not used a sewing machine motor, but they are durable and if you pick up the pedal control you could get a fairly fine range of speed adjustment. Let me know how it works out!

CaffeineMan said...

I am sticking with the motor I have (1 project at a time for me). How do I remove the cam? I removed the single bolt pulled the plastic off, and tried to pull it the rings off with pliers. I also tried using a knife to pry the rings up, no luck. When you say cam I assume you mean that washer looking thing about the size of a 50 cent peace with the raised almost closed o. Pics if you request them.

Phil said...

They are normally just tapped on, but send a couple photos to my email and I'll see if I can help.