I just bought the jeep recently. I figured out why the "Part-Time" light didn't work. it was a bad switch. Now the issue is that 4Hi still does not work. shifts fine into neutral and 4Lo. Messing with the linkage now but still having no luck. Still stumped on this one.

 

Ya gotta watch this. In the interest of science, of course.

 

Select-Trac is the 242 transfer case.
Command-Trac is the 231.

 

Don't take this the wrong way, I mean no disrespect to you here...
I'm having a hard time understanding how you managed to miss 4hi, as if you can shift into 4lo then by simple design of the transfer case (np231) then 4hi is also going to function. As the only differences between the two modes is driving the planetaries. The chain drives off the Mainshaft in both cases. If one works the other does, only 4lo can go out without affecting 4hi. I've been inside these cases extensively over the past few years. Other than the chain or the shift fork, there isn't much to go wrong.

What I suspect you have going on is out of adjustment linkage and what you think is 4lo is actually 4hi .... And what you are really missing is 4lo.
The 231 is quite a simple and basic chain driven case design. 4lo is an extension of 4hi, can't really have 4lo without having 4hi by design.

Have you tried manually shifting the case ... At the range cam lever on the side of the case, through all operating ranges, there will be distinct and verifiable notches for all 4 positions. 2hi, then 4hi, then Neutral, then 4lo.

 

^ Excellent overview and spot on.

 

Should I pull out the quotes and references now? Sorry Op referencing something else, but I simply couldn't resist.
Steve Mongr knows what I mean.

 

I'm no expert, never "cracked" one. I was wondering, if the po had ran it in 4 high forever if that could simply wipe out that gear. If that's even possable, that would explain everything else working but 4 high...There must be some classic saying along the lines of "experience trumps logic!" Not much experience with Transfer case problems here, (other than linkage).

 

It has more to do with how the transfer case operates... If 4hi did not function, then neither would 4lo.
Power is transfered through the mainshaft to the rear output. Shifting to 4hi merely locks the front drive sprocket to that shaft driving the chain and driving the front output shaft. Shifting to 4lo transfers power from the front input, through the planetary assembly, back to the mainshaft using the same front drive sprocket, driving the same chain, turning the same front output shaft.
This is why I suspect the linkage being the issue. Kinda see what I mean.

 

Got it, now I just want a reason to do it. With the 231, should I put it back in 2wd to make a turn, instead of 4hi? I know the 242 has full time 4wd just trying to learn about my 231. Only used 4hi on the road in the snow. If I'm in the woods, or lucky enough to make it to the beach, 4hi / 4lo when necessary.

 

That's what i do in the winter months. When a turn looks tight, ill shift to 2wd and properly take the turn and as soon as im a lil more than half way i pull back up to drive out the turn. I've learn to shift like its a manual car. Constantly using it

 

This may not be relevant, and you probably already tried this - but have you tried putting it into 4hi and then reversing hard and fast for like 50-100 feet?

Even if the light doesn't work (mine doesn't) this usually always gets it to go into and out of 4hi for me (as well as at least 2 of my friends' jeeps)

Also getting offroad (even onto a parking lot with a little bit of snow) helps get me into/out of 4hi some times. Just coasting at 5mph onto a little bit of snow is enough to knock it out of 4hi sometimes when it's being stubborn and won't go back to rwd.

 

TC not going back into 2WD is known as 'spline lock'. The 242 is more known to do this than the 231. Being on pavement aggravates it because it keeps the driveline in a bind.
Going in reverse 5-10 feet or so usually unlocks it.

 

I'll agree with the above linkage issue, if 4L works, 4H (or 4 part time) has too. It is a 231 right? Is everything original to this rig or is it a mixmaster?