It just sat there, not moving, so I waited for the rain to stop and dug into it. I pulled out the rear up and down relays and installed jumpers in their place, the wiper just sat there. Took some power readings at the relay sockets, positive and negative power right where it should be. Again at the relay sockets I connected an ohm meter to the terminals running back to the motor and got 4.5 ohms. That left me with the conclusion that all of the electrical was perfect and it must be a mechanical problem with the motor itself.

I opened the rear hatch, pulled the panel, unplugged the motor and connected my meter to the wiring harness just to see if I was getting power back there. I turned the key to ON and turned on the rear wiper switch...NO POWER. Now if anyone sees what I did wrong give yourself a pat on the back, because when I realized my mistake I quickly called myself an idiot.

Here is my mistake, the rear wiper is disabled if either the rear hatch or glass is open. That's why there was no power back there for my test. So I climbed inside and closed the hatch. Tested the harness again and got power. Okay, definitely a motor problem. I took the motor out, took it apart, used a drill bit and (by hand) spun it inside the hole for the wiper shaft, cleaned the shaft, greased it, reassembled everything, and poof the wiper works again even better than before.

Now to test that I installed the arm correctly so as to not drain the battery, I first ran the motor without the arm and let it go to it's PARK position, then I installed the arm. Then I pulled the rear wiper fuse, which for my 2001 was #12 in the battery box under the hood. I connected an amp meter to the 2 fuse terminals. I then ran the wiper and watched the meter go up and down each time the motor ran. I then turned off the wiper switch and let the wiper go down and park. The meter dropped to zero indicating no power draw, meaning I had the arm adjusted correctly. Took the meter leads out, installed the fuse, and called it a wrap.

 

Nice recap. So was it the motor or the shaft drying out, allowing it to stick?
I know there's lots of discussion here and seem to primarily remember the shaft issue rather then the motor itself?

 

This was on a 1st gen style '01 Navigator? I have a '99 Expy sitting outside waiting for a new water pump and brake pads, where the rear wiper is not working as well. Actually got a code of it saying there's a rear motor circuit failure, so for me that sounds like a failed motor or broken circuit. But, in case of a failed motor, I'd suspect it failed due to a mechanical issue..

 

Last time my wiper stuck, I had my wife activate the switch while I put pressure on the wiper assembly and it "broke" free from the shaft sticking.
Not something you want to do every time it sticks but does work as a temporary fix.

 

Correct, the electrical portion of the motor was perfect. It was the wiper arm shaft that had built up some of that white chalky type of corrosion between the shaft and the bushing it rides in. Once I took the shaft out and cleaned it along with the bushings it all slid together nicely and smooth. The wiper actually moves across the glass quicker than before.

 

The only way to know for sure is to test for power at the motor connector like I did. Remember...hatch closed.

 

I will do that, hopefully the motor is still good. I have an impression that it's pretty reliable motors that rarely fail, but of course, if the shaft gets stuck and the motor keeps trying, sooner or later it'll burn out.. Thanks for the writeup, I'll put that into good use pretty soon

 

I've had trouble with mine in the 98 exp not working except maybe once a year it would accidentally come on. I just pulled the blade and nut off and cleaned up the layer of corrosion on the end of the shaft and spray lubed it real good. Turned the switch to int 2 postion and it was still stuck. Ended up having to push the blade on until I could help it move by hand. That freed it up and sprayed it some more with it running with no blade to try to get some lube inside the rubber seal on the end. It works fine now. Probably just have to spray it every once in a while just like the door latches and locks. Since the shaft sticks tight in that seal it fools you into thinking it must be an electrical problem since you see no action. I've driven it a lot with the switch on hoping something would make it work and that hasn't burnt out the motor or anything. No need to pull the door panel off to look at the motor if you can lube it from the outside.

 

Yes, the shaft dries out in the housing.

Easy fix though.

Get the motor out:


Open up the back cover:


All that yellow stuff is grease that seems to really thin out with the slightest heat (like my hands). Push the shaft out. You may need a hammer to tap it out.

The grit inside the shaft housing:


I sprayed that out with some brake cleaner.

The end of the shaft had some corrosion built up that needed to be cleaned off so it could rotate:

Again, softened it up with some brake cleaner. Wiped it clean with a paper towel.

Then I spread some of that extra grease onto the shaft and stuffed it into the hole. The tolerance between the shaft and housing is pretty tight so it will just squgee most of it off.

Reinstall. Remember to close the tailgate before you try it because the circuit is dead with the tailgate open.

 

Thanks. I saw your how to somewhere else which give me the idea to just try cleaning the end of the shaft first since yours just showed corrosion on the end. Mine had a layer of hard crust twice or more thicker than yours which cleaned off on the outside at the seal. I think I got most or all of it but will see over time. The back end of these trucks catch a solid coat of dirt every time I drive down a dirt road and after snow storms. Probably have to clean it fairly often. When we first bought it the wiper quit and the stealership replaced the motor under warranty. Probably a just throw parts at it kind of deal.

 

For them it's more cost effective to change the part rather than pay the labor to disassemble, clean, and then reassemble it all.

 

I am having the same problem with mine but unlike yours the gear in mine is missing some teeth:



so there is a new motor in the future for my Expedition the shaft was tight in the housing but no sign of corrosion. (Unless somebody knows where I can get just the gear?)

Mark

 

Junkyard.....

 

Ditto that. Even if they have one with a bad motor for dirt cheap, because all that's needed is the gear and shaft.