Good explanation here.
Many will try to use part time 4WD in the rain, I never do.
You need some slippage ladies and gents when using 4WD hi or 4WD low with a part time system.

http://www.4x4abc.com/4WD101/def_turnpart.html



Here is why a full time 4WD can be used on pavement.
http://www.4x4abc.com/4WD101/def_turnfull.html

 

So is the AWD button on my '99 limited considered part-time or is it similar to a full time set-up and safe for the asphalt? I was under the impression that this was the only setting safe for use on road.

 

Good question Hoopster- I have the AWD option on my 02. I always thought that it was ok for on the road (snow or possiblity of slippery conditions). My traction control still works in AWD mode. Are we wrong in assuming AWD is safe for the pavement?

 

I am not 100% sure the system on your vehicles but as long as you can put it in AWD without locking the center differential, you should be fine. If the center diff is locked then it would not be safe to use on pavement. Someone correct me if I am wrong please.

 

i dont know why, and i cant read that diagram, but i do know 4x4 is bad to use on the pavement. this kid at work, (todays his last day btw) said his friend made a jeep cherokee into a dragster, and uses 4low to get up to speed. does this sound idiotic? i mean i know it helps to get up to speed, if you do it the right way, but doin that on the concrete? OUCH!

 

I use mine in heavy rain, sometimes....and I avoid tight turns.

 

Good thread. I know the times I have tried out a 4WD veh, it feels really bad on pavement. I have and Infiniti QX4 and it's kinda weird. It has a switch for 2HI, AWD, but then also has a transfer case shifter? WTF? I've never moved that, when driving in snow, i'll just turn the switch to AWD and it does great.

 

I have two different options in high-
1. AWD- without center diff locked (VSC- on)
2. 4x4- with the center diff locked (VSC- off)
Option on seems fine on the road but option two is not for road purposes

 

I do believe AWD is OK on pavement as mentioned the center diff is not locked.

The FJ Cruiser with the 6 speed manual tranny is full time 4WD, hence lower MPG than the 5 speed auto like I have.