Not exactly sure what you meant about the driveshaft....
Never mind, reread it and I understand now.
There are two things that have to work for you to have 4wd. The shifter on the transfer case is working, because the driveshaft locks.
The other is the actuator on the right front axle. I think that they are still using the boiling fluid system.
There is a cylinder mounted on the shifter on the axle tube that has a liquid in it. When you shift to 4wd, a heater boils the liquid and the pressure causes a shaft to slide out and push the shifter yoke over to engage the right axle.
The problem with what you said, is that on most models I remember, there is a switch on that shifter that turns on the 4X4 light when the shifter moves.
On all my friend's trucks, I always tell them to wait for the light because it takes a few seconds for the fluid to boil.
The colder the weather, the longer it takes.
Also, if you switch the truck off, the power to the cylinder goes off and it shifts the axle out of 4wd, so you have to wait a few seconds for the fluid to boil again after you crank up.
If they do not have the switch on the axle anymore, then its probably a bad cylinder or the wire is loose or bad.
If they do have the switch, then the shifter moved, but did not engage the axle for some reason.
Either way, the test is simple.
Jack up the right front, Take that cylinder off, and push the shifter in by hand and see if the axle engages.
If you see where any liquid has leaked out the cylinder, there is no need to test it. Otherwise, you can put 12 volts to it and see if the plunger moves out.
If its bad, which is the most common thing, you have two choices. Replace the cylinder, or go to the conversion that Warn makes.
It replaces the cylinder with a piece that has a actuator cable.
You run the cable into the cab, and it works like a choke cable.
Just pull or push a knob to move the shifter.
Lots of folks don't like that and want to stay stock. Personally, I like the more positive system.
I have helped install the kit on two different trucks.
The first one was when it failed in the swamp, then a couple of years later the same guy bought a new truck, and we put a kit on the next day.
He did not want to have to get pulled out again.
Of course, all these were several years ago, so they may have modified the system in 2002.
If so, I'm sure someone here will chime in.
But its fairly obvious, just slide under and look at the shifter on the passenger side axle tube.
If its not the cylinder, and its getting power, I have heard of some cases where the bushing or bearing the supports the right front axle on the shifter end wearing to the point that the shifter does not line up right any more.
But you should be able to tell that when you try to shift it by hand.
