spjohnson1031

Hello all,

I'm new to the whole 4x4 situation and had a question regarding the drive selector in my 2001 Cherokee Sport. When placed in 4-High, a "Part Time" light appears on the dash. I have not yet put it in 4-Low, but I presume a "Full-Time" light appears on the dash. What's the meaning of these two terms and what's the difference between them?

aroundincircles

spjohnson1031

Thanks for the video. My question is this. If driving in say, somewhat potentially slippery conditions, like snow, is it okay to keep the gear selector in "part time?" Everyone talks about binding driveshafts in part time, so is it okay to keep it engaged even if not slipping, but in potentially slippery conditions?

93_xjcherokee

You should be in full time if you're in ice and snow

sycoglitch

Our jeeps have shift on the fly technology. So when you see ice or snow up ahead you release accelerator and shift to part time and then proceed to drive. Once the conditions pass, then you release accelerator, go to 2hi, and continue.

If you have the np242 TC, with the 4 FULL TIME option. The morning you hear there'll be icy conditions, start jeep, shift to 4 full and have full all day.

I have a 231 TC and with a decent set of tires, I've never had a real issue. I've been in several blizzards and hurricanes and even down pours and shift of the fly has been great. Also having the proper weight foot helps too

caged

4 low will also light up a part time light. part time means you can only use 4wd part of the time, like only on slippery surfaces. this means dirt, mud, snow/ice. something that can induce wheel spin so if the axles start to bind, the wheels that can spin will so you don't get bind.

if you have a selec trac jeep, you have full time option (np242) transfer case and your first selection is full time and can be left in that position for all surfaces or full time.

if you have command trac jeep, you have a part time transfer case and 4wd can only be used part of the time.

ehall

Yeah you don't have Full-Time if there's not a position for it on the shifter

Part-Time locks the front and rear driveshafts together. This means the front and rear differentials will be forced to spin at the same speed, regardless of what the wheels are doing. When you take a turn, the front wheels travel a larger arc than the rear, but this is not possible when the driveline is locked. If you use it on dry pavement, you'll end up stretching or breaking something (or forcing the wheels to hop). Likewise if you use it on slippery surface, you are going to force the front end to break surface traction, which is probably not what you want. You should only use Part-Time on loose surfaces that will allow the wheels to slip safely, like dirt, gravel, or loose snow.

Full-Time is an extra mode in the Selec-Trac that uses an open differential (like in the axle) to allow torque to move between the two driveshafts according to resistance (wheel speed). So when you go around a corner, the front wheels go faster and have less resistance, so the torque shifts to the front driveshaft. This makes it good for dry, slick, and loose surfaces all the same.

spjohnson1031

Thanks for the help everyone. What would it take to convert my part-time to a full time?

sycoglitch

Finding an NP242 in the JY and getting the shifter bezel, the TC and the linkage, etc. Someone else needs to say if you'll need the DS cause I'm not sure if the 242 has a longer output shaft

cruiser54

Here's how the factory suggests you shift the transfer case and I've been doing this since these things were new and I worked at the dealership. Quoted from the owner's manual. The suggestions in CAPS are mine.

"To engage, shift the transfer case lever from 2H to 4H while the vehicle is moving at any legal speed". I LET OFF THE GAS, THROW THE LEVER, TAP THE GAS AND LET OFF.

4L position: " To engage, slow the vehicle to 2-3 MPH , shift the transmission to Neutral, then shift the transfer lever to the right and pull firmly rearward to 4L".

TO SHIFT OUT OF 4L, SHIFT THE TRANSMISSION INTO NEUTRAL WITH THE VEHICLE STOPPED, SHIFT THE TRANSFER CASE LEVER TO 2H, THEN THE TRANS TO D IF YOU HAVE AN AUTOMATIC, OR INTO FIRST GEAR WITH A MANUAL, AND CONTINUE ON.

Revised 11/20/2014

prerunner1982

This is what your transfer case shifter bezel would look like IF you had FULL TIME 4wd.



Sounds like you don't have this which means you have the PART TIME 4wd and as mentioned is for part time use on slippery surfaces only. The slippery surface must be present. Your transfer case shift bezel probably looks like this...




4lo should only be used when you need slow speed with more torque.

spjohnson1031

Thanks for all the help guys, I appreciate it.

Dumajones

1989cherokee

When you guys are off roading, if not in 4 lo, are you in 4 Hi or part time?

ehall

Depends on the conditions. If I'm going fast usually FT for the improved traction. If I'm going slow for obstacles then usually 4-Lo PT for torque