Wiper motor keeping me off the road! (rotor shorted?) (1 Viewer)

[Bluegrass40]

So I jumped into the pool and got my first FJ40 (78) a few weeks ago! It's pretty sound mechanically but there are some electrical issues. The most important problem to fix first is that the wipers don't work. Normally I wouldn't care about this a whole lot, but its keeping me off of the road (legally at least) bc I can't pass inspection to get the truck registered. I'm ready to get behind the wheel for a trip longer than around the neighborhood!

I pulled the wiper motor out of the truck and started checking for proper electrical connections. I found that there was a short between 3 of the terminals on the connector that leads to the motor. I pulled the rotor out and found that all of the poles were shorted to each other. My only guess is that the insulation on the winding is shorted somewhere. Seems to me like it needs to go in the garbage and be replaced.

Is this common? Is there anywhere that I can get a replacement rotor or do I need to spring for a full motor asm? Any other thoughts?

 

[Fuzzy Logic]

You need to get a FSM. The solid blue wire is hot, the others are grounds. That's how the speed are acquired, through grounds

 

[Volcanic Iceberg]

Sometimes the gear boxes get gummed up causing the motor not to turn freely generating a lot of heat. Pull it all apart and re-grease. Note: the little metal connector plates on the front of the motor control the rest position when you switch wipers off. they have to be exact and are hard to fix if you bend them so be careful. I've seen these motors sell for $400 working, so id suggest rebuilding rather than trashing.

 

[bj40green]

Here is the diagram from the FSM.
The resistance between B and +2 and B and +1 is very low.
It's easy to think that you have a short while you're measuring continuity. The trick is in the park switch. This switch is overruled as long as the wiper switch is in the low speed position. When the wiper switch is in the off position the motor stops when the disk reaches the gap. To prevent that the motor makes an extra half turn the park switch makes a short between B (to S) and +1 so the motor stops immediately.
Hard to analyze from this diagram but that's how it works.


+2 = High
+1 = Low
S = Stop (off)

Here is a very good write up on wiper science: -► http://www.globalsoftware-inc.com/coolerman/fj40/5G.htm

Good luck with the cleaning and lubricating.

Rudi

 

[Bluegrass40]

Thanks for all of the info guys. I'll get into it again today and see what I can figure out.

 

[Tancruiser]

Let me look through my stuff I may have one I will give you . pm me

 

[Bylunda]

check this out.. http://www.globalsoftware-inc.com/coolerman/fj40/5G.htm Coolermans hard work and documentation of it has been a huge help to me!!

 

[Bluegrass40]

Thanks to everyone! Ended up being a wiring issue. Thanks for all of the help. Now I'm pulling out the linkage. There seems to be too much friction in the linkage for the motor to move the wipers. I'm guessing they have not been used for a while!

 

[taro]

Once you get everything working, also keep in mind that I think there are two grounds in the windshield and if the windshield screws are not tight enough, the windshield wiper motor won't be grounded and won't work. Good luck!

 

[JeffD]

I'm in the same boat, tried rebuilding mine with no luck. If anyone has one to spare, let me know a price? 1978 FJ40 located in NY. Thanks.
Jeff