OK i have a 2001 f150 supercrew lariat 5.4L 4x4 and i was at a construction site the other day and it happened to be muddy out there so i put it in neutral and switched it into 4x4 low and it did what it normally does clicks in and then i put it in reverse then drive but this time nothing works the front tires arent engaging and it stays in 2x4 but it shows on the dash that its in 4x4 low... SO i was wondering if these trucks are vacuum or electronic? im not sure but if its vacuum its a easy fix but i cant tell if it is or isnt.
Can anybody help me? Thank you for any help

 

I think, and I'm sure that I will be corrected promptly.
It is both electronic and vacuum. Check every line and fuse
you can find and start there. Lood at the right side firewall/fender
hook ups.
not much help but good luck
Jay

 

thank you i will do that and if anybody knows anything else that would help

thank you all for help

 

Someone will be sure to respond/correct this to this but there is something about a vacuum pump and this may be where your problem lies. I believe it is located on the front axle? maybe? just a start?

 

I just had mine all apart, there is a vacuum line from the solinoids to the pumkin, from there, it goes into the bowels of the front Diff.

 

alrite thanks guys
i was messing with it some more yesterday and when i put it in 4 wheel drive or low range it goes into the gearing but just does not engage the front wheels
im not sure what that means im hoping my gears arent stripped in that front diff

 

There is a shift fork in the front diff that the vaccum motor moves to engage the front axle. This is what is broke, pretty common.

 

You are probly right, do you know how to get to it? and can i buy it at oreillys or autozone?
thanks

 

The fork may be stuck. My 97 sits alot, and the front fork always sticks. I have to crawl under and work it back and forth then spray it with lube.

 

I have a 09 f150 4x4 with a manual engagement. it seems to do the same thing, shows it is in 4 low but does not seem to be turning the front wheels. Any ideas?

 

Just a hint for you 4x4 guys, engage the system once a month. This keeps things freed up and working. Never had a problem with my 01 doing this.

 

how many mies? Is there a lot of salt on your highways in the winter? do you mud a lot? I know a lot of questions but i just replaced my vaccum motor on the differential that the inside just rotted away and quit working. all it is, is a diaphram in there so i suppose moisture and corrosives could ruin it over time. any way take it of and if it rattles around i bet thats your problem. also there is couple of pumps on the firewall, can't remember which one it is but it can go bad also

 

Good Advice!

 

I've read there are also vacuum lines behind the battery that get corroded and they are connected to the vacumm pump on the front diff. There are a lot of posts on this forum that go over the systems involved but it's a hunt for sure!!

Also the dealer said there is a shift motor on the transfer case that goes out frequently too. I've never looked so I can't be sure.

 

My '97 was having the same problem. I took the little vacuum thingy off the front axle, welded a shaft to the fork, ran shaft to the front of the truck and through the top of my skid plate, put a handle on it and some holes in the plate. Now I have manual hubs. Works everytime. The only thing I don't like is sometimes you have to rock the truck to get it locked in.