Need Wiper Motor Wiring Diagram

[tluz]

Hi, Guys,

I'm taking apart the wiper motor of a '63 Avanti. Armature looks OK, brushes probably need replacing, but a couple of the wires to the harness were broken and it needs rewiring. Is there a wiring diagram anywhere? The shop manual is not specific.

Thanks,

Tom

[Milaca]

Try this link and tell us if this helps.

http://studebaker-info.org/PDF/PMA-4001wipermotor.pdf

Brent's rootbeer racer.
MN iron ore...it does your body good.

[tluz]

Thanks very much. This helps a lot.

[gordr]

That .pdf files apparently refers to non-Avanti wiper motors. I took an Avanti wiper motor apart today, and it did not match the diagram there. Two brushes, not three. The field has two windings. One has relatively few turns of thick wire, guessing maybe #22. One end of that winding connects to the ungrounded brush, and also to one end of the park switch. The other end is brought out to the black wire in harness. The other winding has many turns of finer wire, maybe #30, and both ends are brought out to the red and yellow wires in the harness. There is no internal connection to the brushes that I could see. Or measure with an ohmmeter. The blue wire in the harness goes to the other terminal of the park switch, and the white wire is ground.

Got the motor working on the bench. Have yet to test it in the car with the switch.

[64V-K7]

That .pdf files apparently refers to non-Avanti wiper motors. . . . .Got the motor working on the bench. Have yet to test it in the car with the switch.

Thanks, I'll make a note on the page regarding the motor...
...BTW, don't forget the switch in an Avanti has to be grounded as well as the motor for the system to work..

[gordr]

Yes, I know that. I had it hooked up before servicing the motor; switch dangling on the wires, power and ground provided by clip leads, and when it went to "park" smoke came out...somewhere. And the leads were plugged into the switch right.

The bushing on the motor arm is eccentric, with a stop device incorporated. I believe that to park, the wiper motor reverses, and does half a sweep or so, and moves the eccentric bushing to the opposite side of its "run" orientation, so as to pull the blades down tight to the windshield bottom.

[gordr]

Further to the wiper motor issue. Today I constructed a truth table for the switch, and got it sorted out. Yes, the motor does run in reverse, and parks the blades a little lower than their running sweep. I will draw a couple of wiring diagrams later, and scan and post them here. Two diagrams will cover it; there is only one set of connections made in the "run" position. Speed control is continuous over a small range by means of a small rheostat incorporated into the switch, which varies from 0 to 37 ohms, and controls the current through the auxiliary field winding. The auxiliary field "bucks" the main one, so max current through the auxiliary makes for the slowest speed.

To park, the auxiliary field is placed in series with the main field through the park switch on the motor gear housing. When the park switch closes, the auxiliary field (still in "buck" polarity) makes its full field, but the main field's output is reduced because its current flow is limited by the auxiliary field. So the motor reverses, and when the rest position is reached, the park switch opens, and no current flows anywhere in the system. Fiendishly clever, eh?

What it also means is that adding an interval wiper controller to this system would be a real PITA, because the "park" and "run" functions are so different, circuit-wise.