I read this on a website (http://4x4abc.com). Does this apply to the Xterra? On slick paved roads, should I put it in 2WD or 4WD? If this is true, it seems that I should stay in 2WD when I am worried about stopping, and put it in 4WD when I am worried about starting to move forward.

"ABS does not work with part time 4WD systems.

"ABS would work as long as the vehicle stays in 2WD mode. In 2WD all 4 wheels are able to rotate at different speeds (made possible by the differentials) and more importantly in 2WD both axles are allowed to turn at different speeds because the drive shafts feeding power to the axles are not connected.

"As soon as you would shift into 4WD the two drive shafts become connected inside the transfer case and both axles would be forced to turn at the same speed. More importantly, when braking both axles will be slowed down at the same rate (any brake proportioning will be out of force) and the ABS system would get confused. After all the ABS's job is to detect variation in wheel speeds and act accordingly. ABS would not function properly on part time 4WD systems."