I used the four wheel drive in my 2001 for the first time - it seems to be intermittently working and not working - is there something special I need to do to put it in four wheel? What about maintenance??? I ended up having to put it in four low because the four high never seemed to catch?? is that possible ? thanks

 

Is yours manual or auto hubs? If they are auto it sounds like you have vacuum leak on one of the lines going to them.

 

https://www.ford-trucks.com/forums/8...uum-leaks.html

You should be able to turn the selector switch for 4high.4 low you will need to lock in hubs,put in neutral,step on the brake and turn the selector to 4 low.

 

They are auto ... must be a leak... I was fine for awhile then coud not get up a small hill...had to back down. Later on it was fine..then not fine....finally put the truck in neutral and put the switch to 4 low...after that it seemed to "stick".... have to say the truck did pretty darn good when I could not get the 4 wheel to work!!!

 

One easy way to tell....

With the engine running, turn on your heater to blow on your feet. Then turn the selector to 4HI. Wait a few seconds...if the air changes to blowing out of the defrost vents, then you have a vacuum leak in your 4x4 system for the hubs.

 

If there were a vac leak 4Low wouldn't work. It might be one of the two ESOF relays. They are designated 4High to 4Low and 4Low to 4High. I'd swap them and see if 4High works and 4Low doesn't.

If you have trailer tow package don't get them confused with the trailer tow relays that are closer to the firewall. Also the trailer tow relays are 4 pin relays, no break conact,and cannt be swapped with the ESOF relays that are 5 pin and have a break contact. The break contact is necessary for ESOF to work.

ESOF Relays.

 

Good point.... But my question would be...did 4lo actually kick in or did it just change the t-case to low range and still in 2wd?

 

That is a good point as well.

 

I am 99% sure the 4 low is engaging and not the 4 high...is that possible or am I crazy? I am also pretty sure the 4 high worked on Friday...I was having trouble going up hill, switched it over and went right up.

Driving to work this morning I had to go up a couple very steep snow packed hills...before I got to the big hills I tried the 4 high and was not getting good traction...I stopped, but the truck in neutral switched to four low and heard/felt it turn over...I got up the hills fine so I have to say it is working or I just had enough momentum but i doubt that as I was not slipping/spinning at all.

Once the big snowy hills were over I stopped and tryed to switch back to 2 wheel.. it was not disenaging - drove up the last snowy hill and stopped again before getting on the highway - it took several times to disengage but finally did.

Thanks again for all your help...you save me good $$$$ when my glow plug relay went out!

 

My last trip out in the desert I was in 4 high and went to turn around and my back tires spun trying to go over a little hump. I knew right then that my front hubs weren't locking in. You won't really notice anything different when it 4 high except maybe some binding when you are turning hard going slow.

As Billybob said, put it in 4 wheel drive and see if your vents go to the defroster vents. That is exactly what happened with me. 4 low changes the transfer case so the low range is very noticeable. That doesn't mean that front hubs are locking though.

It sounds like you have a small vacuum leak that depends on on the movement of the truck if the hubs lock in or not.

 

It's snow time here and I just fired up the 4X4 for the first time in months. I had a bad ESOF last year and the defrost vent was on full time. Replacing the ESOF got the vents and the 4X4 to work normally again.

I shifted to 4X4 this year with the heat on and I heard the vent switch to defrost for a moment and go back to heat - I know this symptom now. I put my head behind the front wheels and found one split vacuum hose going to the hub (at the connector). I cut off the last inch of hose and reconnected the hose - problem solved.

 

I am having the same problem. 4 high nothing, put in neutral, select 4 lo and it sounds like it is engaging but no 4 wheel drive. I even had the hubs locked in. Could this still be a vacum issue? Going to do the defrost test when I get home from work.

 

If you are manually locking the hubs (no vacuum needed) and still have no 4wd it sound like the X-fer case shift motor isn't working. Can you hear it try to shift the X-fer case?

Also manually lock each hub and try to turn each drive axle. If they turn the hubs aren't locking.

 

Yes it sounds like it is shifting the transfer case but it obiviously is not tottally engaging. I will try the individual hubs when I get home. Worse time to find out that your 4 wheel drive isn't working is when you get stuck and need it.

 

Is the 4x4 dash indicator coming on when you switch to 4 High? What about the Low Range indicator when you switch to 4 Low?

Sometimes you have to slightly move the truck forward and/or backward for the X-fer case to engage.