wiper issue

[jake]

82 fi car:

Intermitten and normal speed wipers work fine. When I switch to high speed the wipers will do about 10 passes, slowing a little each pass till they stop. It fails to park the wipers. My charging gauge on high speed doesn't show a drop like normal or intermitten speeds do either. I haven't had a chance to check voltages. Looking at the wiring diagram I'm not sure what to expect due to no labels on which the high speed circuit is...

Any ideas?

 

[TonyK]

Wiper motor design.

Electric motors normally have 2 brushes at 180 degrees apart. A 2 speed wiper motor has the same but to slow the motor down a 3rd brush is added about 30 degrees out of sync. This is a cheap but effective way to slow the motor down and not loose it's torque characteristics. So on slow speed the motor is using the out of sync brush holder set. I suspect that the high speed 180 degrees apart + brush is bad, hung up in the holder or the wire to it has a poor connection that is heating and increases resistance after a short time to not allow it to pass current.

That should get you started of where to look.

TonyK.

Grimsby Ontario Canada.