This is what I have done for my "'02 Grand Caravan" it may be similiar, it may be total different, but;
One of my electric windows stopped working in our '02 Grand Caravan in cold weather, really cold, and of course it happened when the window was down.
Short of it all, I cleaned up the "COMMUTATOR & BRUSHES" on the electric motor and its been working great ever since. The commutator and brushes were black with carbon worn off the brushes and a little gummy, probably from the grease/oil used in the nearby gears and bearings. The dirty commutator was probably either insulating or shorting the electric current, eitherway, it worked perfectly after a little simple cleaning, it was just getting down to the armeture that was the tough part.
Pull the door panel, you may have to pull the speaker and plastic protective sheet over the door to get to the WINDOW REGULATOR (its the entire assembly/mechanism that raises and lowers the window, the motor, gears, cables, everything minus the guide rails)(Why is it called a regulator? I don't know, but its a typical industry term for the whole window raising and lowering mechanism). The motor should be mounted in the Window Regulator, you want to pull the cover off the motor, in my mini-van I had to loosen all the nuts on the regulator to tilt it a bit to get access to the screws holding the motor case on. Once I pulled the motor cover screws, and slid off the motor cover (the cover has permenant magnets mounted in it.) The armeture has one of its shafts with the worm gear machined into it, so to remove the armeture is to turn it the correct direction to unscrew it from the gears and the whole armeture should back out.
Blow the dust out of the cover, armeture and the brushes.
Square up and smooth the brushes (still in the regulator) with a nail file.
Clean the Commutator (the copper contacts the brushes run on) with a scotch bright pad.
Put it all back together, test it (before you put the door panel back on, in case it doesn't work) and finish up.
Hopefully its the same for a Jeep, I would think so, hopefully someone will chime in if I'm wrong.
