I just recently bought my first Ford truck and only the second 4WD vehicle I ever had, so I am kinda clueless on what I am doing. I bought my 2000 F350 Superduty CC 7.3L (240,000 miles) truck from a used car lot about 3 months ago. When I was test driving the truck at the car lot I was only able to take the truck out in a gravel parking lot out back to check the 4wd. The 4WD seemed to work fine as long as I used the manual hubs, the automatics didn't seem to work. I didn't know and still don't know what the proper procedure is to engage the 4WD. I wasn't 100% comfortable that it was working properly.....but I bought the truck anyways. So I was out today cutting firewood for the winter and needed to use my 4WD and it didn't work. I tried locking it in Manually and I tried using the Automatic switch on the dash. I tried driving forward and in reverse and all I did was spin my back tire. I made sure the hub was switched to "Automatic" when I was using the switch on the dash. I don't really care to have the "Automatic" to work just as long as I can manually lock in the hubs. So being a semi-newbie - What are the first things that I should check or do? I tried searching threads on here but couldn't really find anything. I think this is a really great site, I'm glad found it. Any help will be greatly appreciated. Thank you.

 

http://www.guzzle7pt3.com/allube.php

check this out on how to lude the hubs. i am about to do the same thing on my 1999 f250

i see alot of people here switch to warn hubs that are manual only. they plug the vacuum lines that make the auto hubs work.

 

Does the lack of lube also cause my MANUAL hubs to not lock in? Thanks for the post fishpimp.

 

When it wasn't working the last time, did the 4x4 light come on in the dash?

 

I don't think the light was on. The only way I was able to tell was by how the truck was driving.
What do you think should be the first thing I check?

 

Check to make SURE the light wasn't on first.

 

I'm NOT getting a light showing that my 4WD is working. Now what?

 

That means that the transfer case is not shifting. Check the 4x4 fuses, and the relays in a small box near the main power distribution box. If you swap the two 4x4 shift relays, it might go in but not come out. Swap them back and it'll come out.

Do you have a clicking from the transfer case when you move the switch from 4x2 to 4x4?

 

The next step could be the 4x4 module................expensive, but open your door and lower your head to listen for the click then try swaping relay like Krewat said.

 

Should I hear the clicking sound with just the key on, or does the truck need to be running? I swapped the fuses and the relays.....it didn't change anything. What's the easiest way to know if the fuses are good......I noticed there are 4 prongs on them...which ones should show continuity? Thanks guys.

 

I doubt if all of the relays are bad .You should easily hear the click with the door open and engine running. (I never tried it not running) There should be a click using 1 of those relays, either going in 4WD or out.

 

First of all, make sure you're looking at the right relays. There are two or three small relay boxes under the hood, on the drivers side towards the rear. You want the relay box that just has two identical relay's in it, with nothing else.

Check for corrosion of contacts and wires. With the key on, engine off, turn the switch to 4x4 and you should hear one of the relays click. It ought to try about 3 times before it gives up. And it's not a loud clicking, so you may want to be very close to them while you have someone turn the switch for you.

One of these relays is responsible for turning the shift motor from 2wd, to 4wd and then to 4WL. The other relay is responsible for turning the motor the other direction. This is why swapping the relay positions is a good test. Since it's unlikely for both of them to go bad at once.

Also, in my case the shift out relay was still activating (clicking), but it wasn't making contact inside and I was stuck in 4WL. Once I found and swapped the relays it shifted right out, but then since the bad relay was in the shift in position it would shift back in, etc.

 

Thanks David, and if that doesn't work it might be the 4x4 module (unclear if it is part of the GEM module). Check your wiring also.

 

I don't hear any clicking. How do I know if the fuses are good?

 

I'm just looking through your owner's manual. It may be that the GEM module is bad or isn't getting power. Try checking fuse # 15 and 19 in the fuse panel under the steering wheel and fuse #17 in the fuse panel under the hood.

This is a link to your owner's manual.
http://www.motorcraftservice.com/pub.../00f23og3e.pdf

or a link where you can search and find all of the manuals that would have come with your truck.
GENUINE FORD AND LINCOLN MERCURY PARTS AND SERVICE – GLOVE BOX MANUALS REPLY PAGE – MANUALS NOT FOUND