Re: 4wheel drive problem
You refer to the TCCM (rest of the world), or sometimes known as the GEM (Ford spec). This can be replaced and generally solves electronically controlled transfer case problems. As for the button, I can't speak of that as I'm not sure what it does.
Oh, at the rear of the vehicle, you may have a fuel pump shut off switch. I didn't think it was in earlier Explorers, but I could be wrong there. In the event of a rollover, or if the computer thinks a rollover is eminent, it'll shut off the fuel pump to prevent engine run on and possibly a fire, should you be involved in an accident or rollover. The button reactivates the fuel pump so you can go back on your merry way. The TCCM (GEM) is generally located under the dash around the drivers footwell toward the center console.
If you have a manual transfer case (shift lever on the floor), then the forks in the transfer case might be broken, and you may need a rebuild. However, as you can get into 4HI, it might be an easier problem to fix. Only way to know for sure is to take off the Tcase cover and have a look.
'00 Durango R/T 360ci 290hp (modded); 138,500m
'06 Pontiac G6 GT 3.5L 220hp; 44,000m
'12 Chrysler 200 Limited 3.6L 283hp; 13,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!