Read the article:
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=18

That should help answer your question.

Here's info  on the "brown wire mod" with pictures for the 1995-1996
Explorers:
http://tinyurl.com/y5hzu9

Here's the "comprehensive brown wire mod" info, covering '95-'96 and
'97-'01 model years:
http://tinyurl.com/ycyp54

Note: not for AWD vehicles.

Why do this mod:

Some of us simply prefer to determine when the front wheels should
drive and when they shouldn't, instead of relying on a computer to make
that decision for us.

Background on the "brown wire mod":
There were three slightly different systems included in the
second-generation Explorers. The All Wheel Drive is a full-time system
and cannot be modified to be full-time four-wheel drive or two-wheel
drive. The second and third systems used in the '95-'96 and '97-'01
model years were both called 'Control Trac 4 Wheel Drive' Both systems
used the (insert model here) transfer case. The '95-'96 used a front
axle equipped with a Center-Axle Disconnect, which was done away with
on the '97 model year in favor of a live axle (and fewer parts to fail
when needed most)

Depending on the operator selection, the transfer cases in both systems
were actuated by one of two GEM-controlled sources: The Torque On
Demand Relay and the Transfer Case Shift Relay. The transfer case
contains a Transfer Case Clutch Coil, which is what locks the front and
rear driveshafts together. Power for the TCCC is fed via a brown wire,
hence the familiar name.