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4WD died for a bit


PaulZ

Well-Known Member
Joined
Jul 21, 2014
Messages
159
Vehicle Year
1990
Transmission
Automatic
So today I got to my steep dirt driveway, clicked over to 4WH, the dash light blinked several times, never went in. Drove around on the street a bit, no help. Finally gave the servo motor a few love taps, that worked. Lots of rain and wet roads lately and the motor looks a little rusty on the outside. Did water get in and cause this?
 
This happened to me over the summer multiple times, before my 4WD eventually just refusing to work at all. Yes, it is the shift motor. Not sure if water directly causes it, or not but either way they end up dying eventually. You can try to rebuild it (there's a guide on here somewhere), or just replace it. I tried to rebuild it, no dice.

IF you plan to replace, DO NOT BUY the Dorman motor. It does not rotate far enough to engage 4hi without slipping or 4lo at all. Piece of Chinese junk. I bought a reman'd motor from Rockauto.
 
If you do your own work on them that's what I would do. It pulls easy as a starter and cleans up as well also, not really too complicated
 
Mine was a Dorman, the one I bought in 2007, has worked fine, not sure if yours was a rebuild or what.
I have the original in the box it came in, rebuilt and ready to use, the Dorman has been on the truck all these years. Says it was made in Korea
 
Mine was a Dorman, the one I bought in 2007, has worked fine, not sure if yours was a rebuild or what.
I have the original in the box it came in, rebuilt and ready to use, the Dorman has been on the truck all these years. Says it was made in Korea
The key there is you bought it in 2007. Dorman used to be really good, now a lot of their parts have slipped in quality.
 
The key there is you bought it in 2007. Dorman used to be really good, now a lot of their parts have slipped in quality.
Yes sir, I was wondering if it might be something like that.
Now I guess we'll need to check close even "New-Old stock" I wasn't aware :/
 
One thing we have found that minimizes issues is to cycle the transfer case through all the settings at least once a month or more often. The contacts get dirty and/or get some corrosion. Cycling the motor helps keep the contacts clean.

Ofcourse it does nothing to help with a failing shift motor but it does help mitigate other issues.
 
Thank you all for the replies. I plan to pull the motor today for a quick look. Just a regular motor with brushes? Afraid to try a new one with the cautionary comments.

I live several days a week at my cabin, 4wd required, so it normally gets switched then, but as I mentioned it sat in 2wd for a week during the recent wet storm weather. Always worked fine, though 4WL usually took some time to engage.

Are the contacts you mention inside the motor, or the plug outside it?
 
There are wiper contacts within the motor that tells the TCCM (Transfer Case Control Module) where the motor is in its rotation, so it knows how far to rotate and when to stop rotating. If those contacts are dirty or corroded, the TCCM cannot tell where the motor is, and often will simply not trigger it to rotate.

Some T-case motors you can get to the contacts to clean them, others like my OEM the contact module is sealed and if it goes bad, you can't service it.

 
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Thanks Cam, I’ll keep that in mind. But, since my last love tap it’s been working perfectly, so I haven’t pulled the motor. I did unplug and reconnect the external connection. It was clean though. Also ground has been dry since that episode. So at this point don’t know which of those things, if any, made the difference, but not messing with it today. I am testing 4WH every day though.
 
Thanks Cam, I’ll keep that in mind. But, since my last love tap it’s been working perfectly, so I haven’t pulled the motor. I did unplug and reconnect the external connection. It was clean though. Also ground has been dry since that episode. So at this point don’t know which of those things, if any, made the difference, but not messing with it today. I am testing 4WH every day though.
Hey, I can't argue with a little percussive maintenance! :stirthepot:
 
4wd wouldn’t engage again last night. Pulled the motor today, brushes dirty, ok otherwise. That blue electrical piece must do something but it’s working for now.

don’t know if I mentioned that when it won’t engage, the dash light blinks 4wd about 4 times, then goes blank and it stays in 2wd. Same if you try restarting.
 
IMG_2312.jpeg
 

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