Explain to me how 4x4 works in my 99 4runner

[j7b]

My 99runner has:

1) 4x4 button on the side of the 4x4 shifter
2) pull back shifter for 4x4 high
3) push right and foward for 4x4 low
4) Rear differential lock button on dashboard

4 wheel drive as I understand it, means that power is distributed to the right rear and front left tires evenly, with 4 high just being a lower gear for tight situations.

So what's the button for on the shifter; is that some kind of "part time" 4x4.

And the rear diff; does that lock the rear differential so that both rear wheels have equal power with not slippage?

How does 4x4 compare to all wheel drive systems.

[texas12]

This link will probably explain it alot better than a short post.

http://auto.howstuffworks.com/four-wheel-drive.htm

[j7b]

That's a great article.

I think I understand everything except for the push button on the 4x4 shifter. Anybody know what that does? I'm thinking it will engage 4 high if it senses slipage in the rear wheels, whereas if you manually engage 4 high, it's always locked in.

The rear diff is kind of cool then. I've been in situations where both of my right side tires were burried and they just spun in 4 low, while the left side tires didn't move at all. Rear diff should give power to the rear tires equally and get me out of situations like those.

[Darren]

It sounds like you have a Limited, correct? If so, you also have the option of AWD as well, which would be what the button is for. The 4WD shifter is purely to lock the center diff (4WD).

4 high would be for 4WD situations, and the 4 low is the lower gear range set.

You are correct on the rear locker bit. A full, selectable locker. Now get out there and use it!

Compared to AWD, a 4WD system adds a transfer case for low range gearing and is a 50/50 power split to front and rear driveshafts. And as I mentioned, assuming you have the Limited, you also have AWD, which is the best of both worlds. That multi-mode system was not available on other models in '99.