Posted by Keith in Washington [172.69.65.11] on Saturday, February 22, 2025 at 12:24:04 :
In Reply to: Re: 1960 Dodge W300 variable speed windshield wipers posted by Greg Coffin [172.68.35.119] on Saturday, February 22, 2025 at 10:11:19 :
The fact that there are two wires going to the motor says it is a single speed motor. The speed is controlled prior to the two wires. Looking at the switch it has a ceramic housing which means there are resistance coils in it which heat up to lower the voltage to the motor.
You should be fine in applying 12 volts across the wires going to the motor. If the motor spins, then it is the switch. The switch will have a contact that moves along the resistance coil if it truly a variable speed. If it is a multi speed switch then the contact will move from contact to contact thus changing the motor speed.
To test the switch put a volt meter on the contacts that go to the motor and rotate the switch and watch what happens. If no voltage is shower check the input wire to the switch to make sure there is 12 volts there. If there is 12 volts in and 0 out you need to work on the switch.
It appears that the switch can be taken apart by bending small metal tabs which will let you see and possibly repair the switch. It possible that corrosion is the problem or that the contacts or coil has been worn through. The moving contact may not be touching the coil or other contacts with age. If so, you might be able to slightly bend the rotating contact slightly. My guess contacts are worn.
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