What could be wrong with a 1998 Ford Expedition when 4x4 is selected and it lights on the dash but doesn't engage the front axle?

Answer 1

Well, I have a 98 Ford Expedition 5.4L I am also Currently working in the Feild of Automotive and taking classes for SMOG @ Wyotech. I've also had the same problem. The First Thing I did was disconect and reconect the bat, then tried and worked. That told me something was wrong with the electrical and not mechanical. So I waited till it happened again and when it did, I uplugged the connector (power supply) to the transfer case to check if there was debri in between, there was. Blew it clean made sure that the (green)rubber square gasket was placed properly between the connectors. Tried and it worked, then it happen again. So I finally took out the DMM (multimeter) and checked The Switch in the dash, Fusses and the solinoid )on the Transfer case. ALL THAT AND IT WAS THE SWITCH. If it is your switch ....To get to the dash just simply pull over the cover area (radio) with your finger tips (snaps on and off so just pull firm) two little bolts and HELLO THERE MR 4x4. Happy TRUCKIN.

RTMANLAPAS@AOL>COM

NoteThe 4x4 rotary switches, common to Ford and Mazda vehicles, has had an issue for awhile where it would either get dirty and not run properly, or the rotating Tri-prong contact would get bent slightly from use so that there is a poor connection. Simply remove the switch like he said, but instead of replacing it, take it apart and clean it with some electrical contact cleaner or equivilent. Make sure the Moving contact is touching the mini circuit board well enough, and reassemble. The way the swith works is off the amount of resistance in the 4x4 logic circuit. The middle two connectors are for the 4x4, while the outer 2 are just for the little dash light above it. Each position of the switch has a different sized resistor, so when you move the switch, each setting has a different resistance it sends to the 4x4 module or GEM (Depending on the year of your vehicle.) So, if the switch is ok, perhaps it isn't getting enough voltage or the control module is bad. For my problem on my B4000, I'm going with the 4x4 module, all the rest seems to have checked out good. AnswerIt could be on of the fron cv joints, because when one goes out the other one will not work as powerful or probably not at all they both need power in order to work.