where do I located the computer box for the all wheel drive

on 2002 Mercury Mountaineer

When I am driving I am hearing a noise seems like it is coming front wheel when I drive less than a half block, also the abs light stays on all the time.

Asked by for the 2002 Mercury Mountaineer
whatever is setting the abs light needs to be found out. that may be causing the asb motor to run causing noise. have codes checked for abs.