The 2-speed wipers on a car I recently bought don't work. I checked the fuse and it was good. I tried swapping the dash switch with another that I know is good and they still don't turn on. All of the wiring looks good. So I would like to try bypassing the switch and test the motor (while it is still mounted on the car). Which leads on the motor would I need to hot wire from the battery to see if the motor works? Also, is it possible the ballast resistor mounted to the motor could be bad?

Try this

Thanks. That should be a big help.

I'm still having problems with my wipers so I could use some suggestions on what might be the problem. First of all, as I said, the wipers didn't work at all when I got the car. I tried another switch and nothing changed. So I followed the steps for testing in the service manual. First, I tried doing the tests while the motor was on the car and nothing happened. So I took the motor off the car and cleaned the ground strap, the metal bushing that goes over the firewall stud and the stud itself. Bench tested the motor and it works on both high and low speeds. I put the motor back on the car and tested it again by bypassing the switch and jumping the terminals. Still worked properly including parking. The only exception was that the wiper arms have a tendency to stop moving occasionally. If I give them a little push they start again but eventually stop again. Hooked the wiring harness back up to it and tried with the switch in the car. The wipers only work on low speed and the stopping mid-sweep keeps occurring. Again, I give a little push and they start moving. I tried two other switches I have and it's the same, the wipers work on low but will not move on the high speed setting. If I have them running on low and turn the switch to high they stop as if they were turned off. Also, when they are running on low and I turn the switch to off they don't park. They just stop wherever they are at. Any help on what I should look for to solve the lack of the wipers working on the high setting and their failure to park would be appreciated.

When you have everything in the car, how is the ground on the wiper switch? On my Challenger I ended up running a secondary ground wire from the metal frame the wiper switch fastens into to the body of the car. Prior to that the metal frame was grounded via one hold down/mounting screw to the dash. Figured this ground point wasn't solid after almost 50 years. The switch has to have a good ground.

Not sure on two speed wipers, but on three speed wipers, there is a contact inside under the center cover that affects the park feature. I took a mini file and dressed the contacts. Worked wonders.

Grounds, grounds, grounds. If the switch isn't grounded or isn't installed in the dash with a good ground nothing works right. Hold the switch in you hand with power on and touch ground you'll feel it. As for the stopping,the 2sp motor can have a lot of grease inside on the gears. Over time that grease hardens and things slow down or stop moving. Other than rusty outsides usually that's all that's wrong with the motors I get from customers. They can be restored.
Bruce
ns1aar.com

I tried running a ground wire directly from the switch to the dash today but nothing changed. The wipers are still acting the same.

There are 4 different 2sp wiper motors and hard the identify.
69-70 A/B and 71 A are all non reversing motors 5/16 shaft
72 and up A non reversing 1/4 shaft
70-71 E and 71 B reversing 5/16 shaft
72 and up B/E reversing 1/4 shaft

What car do you have

1971 Duster.

does anyone know a vendor that rebuilds wiper motors specifically for B Body Mopars...68 thru 70 ?

Ya me and I also do most other mopar wiper motors
Bruce
ns1aar.com

You need to make sure that all 4 of the terminals on the wiper motor are dull silver. If one is Brass that is the reversing motor and won't work with a-body switch

There are no brass terminals.

That's the correct motor. Try a continuity test on the wiring and the switches.