I have a 1998 explorer and the 4wheel drive will switch on like it should and the lights do not blink or anything but I can tell the rear end doea lock in low but never any power to front axle in any range.. I need HELP!

SOURCE: 2002 Ford Explorer 4WD. 4WD is inopertive.

put a ground strap from your transfer case to your transmission. also with someone listening under the car with the key on but not running put your foot on the brake, shift to neutral and turn the selecter to 4x4 low and see if you can hear the actuater respond

SOURCE: Left rear axle seal is leaking differental oil.

ok then here is the procedure  1 take off the axle nut
2 on the lower control arm you will find a large nut and bolt i belive the nut is a 21mm and the bolt side is an 18mm. this bolt is the one at the knuckle near the brakes. remove it
3 you will need to pull the knuckle out of the way or a helper to pull the knuckle out of the way so you can slip the axle out of the knuckle.( its a tight fit but there is room to slip it out.)
4 use a pry bar to pop the axle free of the diff. hosing its held in by a spring clip make sure the clip comes out with the axle if it gets stuck inside you will have to fish it out.
5 use a pry bar or screwdriver to pry seal out of housing then use a flat object that contacts the entire rim of the new seal so it can evenly be installed with out getting smashed and tap it in with a hammer. ( a good trick here is to use some grease and pack it into the new seal where the spring is this will prevent the spring from being shocked out of the seal during instalation . the spring keeps tension on the rubber in the seal so it stays tight to the shaft it is sealing.)
6 then revers the above steps. also make sure you are using the right gear lube it will most likely be 75w-140 but make sure you check your owners manual will tell you if it doesnt say on the diff cover. you can cause a lot of damage if you put in the wrong thing. and make sure  you feel the axle spring clip snap into place.
as a note there are two types of axle seals that are used on these so if the new seal looks different than the old seal then the folliowing will be important to you.the seals on these have been redesigned so if you axle has what looks like a cup or dust cover pressed onto the shaft where it goes into the diff the new style does not use this and it will prevent the axle form going in all the way so the spring clip will not lock in and you will have a leak. so you will have to remove it and install the axle without it.