Meaning of 4WD Part Time

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kwmir

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I have just bought a 2003 Jeep Liberty Sport and had a question. When I shift the transfer case from 2H to 4H, thee instrument panel "4WD Part Time" lights up. What does this mean? Does this mean that the 4WD is engaged part time? In case of my CJ5 engaging it in 4H mean the front drive shaft is providing power to the wheels hence four wheel drive mode is engaged. Is this not the case in case of the KJ?

Another question I have is that when in 4H or 4LO, making a sharp turn is not easy as is when the vehicle is in 2H. I used to expereince this problem in my '79 CJ and that was normal. I was under the impression that being that the KJ is a 2003 model, technology would have improved since '79. My friend's 2005 Laredo which is automatic swithing from 2H to 4WD does not have this problem.

Someone please shed some light on this issue. Thanks.
 

2003KJ

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The 4x4 part time comes on because there are two different types of 4x4 systems offered for the KJ.

The NP231 transfer case, named "command-trac" offers 2HI, 4HI, Neutral, and 4LO. This is a part time transfercase. Meaning that when you shift into 4hi, you still have the full 4x4 power for as long as you have the t-case in the 4HI position. This t-case is NOT to be used when not offroad, or when the roads are dry. use it when off road, in the snow, in thick enough mud, etc.

The NP242 transfer case, names "selec-trac" offers the exact same features as the 231, but inbetween 4HI and Neutral is 4Full-Time. This is basically an all wheel drive setting. Full time can be used on dry pavement, in the rain, when ever you want it, hence the name. As i said it offers a full time option, but at the same time, you can still completely dis-engage the t-case back to 2wd. This is done by there being a separate differential inside the transfer case, that allows room for the slipping of the wheels in a turn, and just about eliminates the wheel hop/driveline binding you mentioned in your other post.
 

kwmir

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So is it okay to use the 4H (Part Time) in wet/rainy conditions? Why is it only recommended to use this only when off-roading?
 

jfortier777

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kwmir said:
So is it okay to use the 4H (Part Time) in wet/rainy conditions? Why is it only recommended to use this only when off-roading?

Extremely rainy conditions maybe, not just "oh hey, its raining today." conditions.

4WDPT systems require a certain degree of slippage to function properly. a paved road is created for the sole purpose of decreasing slippage as much as possible. The road is flat and all tires have ideal traction. 4WD is meant to propel the vehicle forward when two tires are just not providing enough traction to move the vehicle towards its destination.

But I dont feel like me explaining it is gonna help much.
So here is a very fun and easy to understand HOW TO that can explain it better.

Click me to learn about four wheel drive :)






Click me to learn about the jeep hurricanes drive system(complicated)
 

2003KJ

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kwmir said:
So is it okay to use the 4H (Part Time) in wet/rainy conditions? Why is it only recommended to use this only when off-roading?

I wouldn't. It's not really meant for it, but i've heard others use it in extremely rainy conditions, and not have any problems. I'd rather not take the risk. I'm running Revo's on my KJ and have had absolutely no more issues in the rain since i got rid of my goodyears. Plus if i ever feel it starting to slip in the rain, i'll just back down on the speed a little bit.
 

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