2000 f150 4x4. have front shaft turning but front end will not engage.
Vacuum switch is moving but do not know how far it must move to make things work. dose any one have some ideas I need my 4x4.......

 

There's a shift fork that the vacuum is engaging in the front diff...
Many people have had problems with the fork breaking. It's a good bet that if you get the front drive shaft to engage and you have vac to the diff, the fork is the culprit.

-Kerry

 

I was under my truck most of the night trying to figure out why I was having so many 4x4 issues. Every winter, there is a problem. A few beers later, this is what I was able to do. Here is my story.

Me and the bank own an F150 ford lariat 4x4. Great truck. Anyway, last year the shift on the fly wouldnt work. The light wouldnt come on, traced it to the shift motor on the transfer case, problem solved, easy fix, replace shift motor.

This year light comes on, front end wont engage in hi or low. I checked the shift fork on the front off the differential running from the vacuum diaphram. All was moving back and forth freely. So what I figured from reading these great posts, was that the shift fork inside was busted. Well I crawled back underneath and attemted to take things apart. I got as far as disconnecting the 2 lines to the vacuum diaphram and shifted the forked by hand back and forth, finding that it moved easier unpluged. So what I did was left them unpluged, pushed the fork all the way in towards the diaphram, and tried to turn the transfer case shaft, it wouldnt move, pulled the fork back out, and it moved freely. While turning the shaft freely at the same time, I pushed the fork back in towards the diaphram and locked it again, also noticing it was engaging the front axles. All was working the way its supposed to, so why isnt it engaging when the truck is running?? So I figured I would just jump in the truck and see if it made any difference leaving the vaccuum line unplugged. BINGO. It was working. So when I hit the switch to off, the transfer case dissengages then engages when I turn it back on, all the while the lines are unplugged on the diaphram.
So now all I can figure is that the front end is always engaged but I can still dissengage it from the transfer case. Is that good or bad? I dont know, maybe someone can help me on that one. But for now, I am happy again that I have a working 4x4.

Hope this helps out.....

Troy

 

There are two solenoids on the passenger side firewall... sounds like one's not operating correctly. I'm not 100% sure if they both engage or only one works depending on shift switch position and what the 4x4 GEM reads as inputs from the system.

-Kerry

 

It is all better now $$$$$$$ it had a broken fork broken axel and hub but I got it un stuck the last time I was in the bush. Thanks to all you guys for the input and ideas BOOB.

 

A lot of stuff, on a design that few know about, to go wrong.

Glad to here it's working.

-Kerry