Variable speed windshield wiper?

[msd1107]

Looking at the wiring diagram, there are two wires going to the windshield wiper motor.

I presume one is the full 12 volts, and one is a lesser voltage that comes from the windshield wiper switch.

Now for the question.

If a variable voltage was presented to the high speed terminal of the windshield moter, would it run the wipers at a variable speed? And is this speed linear with the voltage?

A simple rotary potentiometer on the dash or steering column could accomplish this.

What about this? Has anybody done it? Is it possible?

David
1968 36/7988

[john.p.clegg]

David
I suppose you could slow them down by putting a variable pot in line,but wouldn't it be rather large to handle the current?

John

[Frank Howard]

"...there are two wires going to the windshield wiper motor."

David,

I believe there are 5 wires going to the windshield wiper motor.

[bcmc33]

As my 72 Sprint is in pieces, I can confirm that it conforms to the S3/S4 wiring diagrams. Five wires to the motor - four to the switch plus a black wire to ground.

The S1/S2 wiring diagram shows four wires to the motor. One to the fuse box, two to the switch and one to ground.


Brian Clarke

[msd1107]

Sorry guys, I was talking about the two wires carrying +12. It is true, the wiring diagram shows four wires from the wiper switch and five wires to the wiper connector.

I have subsequently gotten a reprint of a Lucas manual. It appears that the wiper motor accepts +12 on two connectors, one of which runs the motor at low speed and the other runs the motor at high speed.

So I would suspect that putting a high current rheostat in series with the high speed connector would give variable speed wipers.

David
1968 36/7988

[triumphelan]

I have just added a bias switch which give one wipe ,it is connected to a switched live and then to the brown/green wire going to wiper motor.This saves the wipe switch

[Foxie]

David,

Whatever the total number of wires going to the wiper motor, depending whether it's single or two speed, there is normally a permanent live, which feeds in all positions except the 'park' position, and a switched live from the wiper switch.

Lowering the operating voltage will slow down and eventually stall the wipers, but it may also burn out the motor.

Hella make a very effective "variwipe " control which will answer all your prayers.

Sean Murray