First check the level of the lube in the rear differential. If it is low add the correct weight lube. If not, then you have worn gears. Also check your rear wheel bearings as that is what you may be hearing.
it may be bad bearing (bore bearings).
The 2002 Ford Explorer has 38.9 in. of rear head room.
The 2002 Ford Explorer has 54.3 in. of rear hip room.
The 2002 Ford Explorer has 37.2 in. of rear leg room.
The 2002 Ford Explorer has 58.9 in. of rear shoulder room.
The rear track of the 2002 Ford Explorer is 5 ft. 1.2 in. (61.2 in.).
The Grinding noise in the passenger rear of a 2002 Explorer is most likely either a bad wheel bearing, or a brake problem. Check the brakes then the bearing to find the cause.
both my rear power windows does not work in my 2002 ford explorer, why?
It's your shocks. You either need new ones, or a whole tightning adjustment.
what is the Torque spec for rear axle hub nut on a 2002 ford explorer
The 2002 Ford Explorer has rear wheel drive.
It is most likely that the fan for the rear heat is failing. Usually the noise is related to a bad fan bearing.