A grab bag of tcase and axle questions...

Hello fellow XJ'rs. I have a few questions that need answers, ive done my homework and did all the searching but with a lot of different questions it gets confusing. So heres the deal, I have an 88 xj, i6, auto, 242, 6" lift, etc...

I first started out with installing flares that are needed to pass safety check. we had a big rain and the insides got flooded, so i figured i'd use the downtime to "Play" with my jeep. Out came the interior, floor was grounded and sealed. then came the bed lining. I had to remove the 4 bolts on the side of the hump which holds the bracket for the shifter (or so im guessing) to get a nice coat down. Ever since i got the jeep the dummy lights have been temperamental (which seems to be a common problem) anyways, after doing so i noticed that the full time light would come on. Other wise when i take it out of 2wd and into 4full there is no light but in 4part or 4 low the part time light will come on. And once taken out of 4wd the part time light stays on for a long while and goes off when she pleases.

Well after laying down the liner i was pondering about doing a homemade posi loc for the front and thought it would be fun and would also take care of the light issue and guessing. So i roll underneath my rig to see how dirty of a job it'll be and discovered that i have the non disco d30 on the front.

so my questions are this:
if the front is non disco, what is the difference between 4 part and 4 full? and when would you use which one? Im used to toys with 2hi, 4 hi, 4lo. I dont understand how there can be a PT and FT if the axles are always locked...

is my setup typical for an 88, meaning non disco d30 and the 242? or did the PO swap out some stuffs and missed on some switches? because when i shift into 4lo the brakes stiffen up 5 fold so i know there is a vac draw somewhere, but if there is a non disco, what is drawing vac?

Ive read a few threads here explaining about a x-over wire (gray yellow, black red wire [i checked on my rig and found those wires as well]) would this be needed to fix my issue? or could it possibly be with the vac mentioned above.

If you've got this far, i thank you for your time and help. Its really appreciated. Aloha :wave:

If your Tcase has full time then yes it is the 242.
Yes your front is probably a d30


For the shift light it may be because she's not popping all the way out of the gear. My 242 usually required going in full throttle reverse for a couple feet to pop it out.
just shifting the handle doesn't usually do it.

YuccaMan said:

NP242 Selec-Trac will not have the disconnect
# All 1992+ are non-disconnect

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If you really think the axle was swapped

Yuccaman again said:

All 84-88 D30s have 5-260x u-joints (1 1/16" diameter caps)

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http://www.yuccaman.com/jeep/history.html#axles

The 242 in full time allows some differential action between the front and rear differentials, part time locks both front and rear drive shafts (they turn at the same speed).
The 241 came with a disconnect, which tended to be temperamental. I've heard they even discontinued the disconnect for the 241 in later models.
You may want to check the splices and wire bundle running on the floor by the drivers side door sill. It lays under the wet carpet padding for years and can get pretty darned corroded and crispy looking.
Wish I could be of more help, I haven't had the problems you describe.

MpSlayer said:

If your Tcase has full time then yes it is the 242.
Yes your front is probably a d30

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Yes, there was no doubt about it being a d30. I just thought all years b4 91 were vac controlled. but after reading your posted links it made more sense. np242 equipped rigs came with the non disco axle.

For the shift light it may be because she's not popping all the way out of the gear. My 242 usually required going in full throttle reverse for a couple feet to pop it out.
just shifting the handle doesn't usually do it.

Click to expand...

Well i got underneath 'er again and made a slight adjustment to the shifter rod ( a simple bolt, slide and retighten) and after tweaking it a bit and losing 4lo, then 2wd, i found the sweet spot where all gears work right and the lights work when they should. with the exception of your advice... when comming out of any 4x4 into 2wd, i need to slap it in reverse for a few feet and then bang it into 2wd while still rolling and then pop it into drive.


Thank yall for your help and to 8mud, thanks for clearing that up about the 4full and 4pt.

808offroad said:

Yes, there was no doubt about it being a d30. I just thought all years b4 91 were vac controlled. but after reading your posted links it made more sense. np242 equipped rigs came with the non disco axle.




Well i got underneath 'er again and made a slight adjustment to the shifter rod ( a simple bolt, slide and retighten) and after tweaking it a bit and losing 4lo, then 2wd, i found the sweet spot where all gears work right and the lights work when they should. with the exception of your advice... when comming out of any 4x4 into 2wd, i need to slap it in reverse for a few feet and then bang it into 2wd while still rolling and then pop it into drive.


Thank yall for your help and to 8mud, thanks for clearing that up about the 4full and 4pt.

Click to expand...

I've had pretty good luck shifting the transfer while I'm braking to a stop to get it out of whatever. Going in is just usually a matter of working the gas pedal a little. Exercising the transfer periodically also seems to help, long periods without use tend to make it more temperamental.
Sometimes I've had to try every trick I can think of to get it out of four full or part time.

My bad. the disco came with the NP 231 in the early years. 241 is what I have sitting on the workbench at the moment .

I'm not so sure the "full throttle in reverse" is a good thing, nor is it necessary to get the vehicle out of 4-wheel drive. I drive an '89 with the 242 and non-disco D30 up front. Shift linkage adjustment is important...and is easy to do (Chilton's or Haynes have the procedure).

Best procedure that works for me...first and most important, don't try shifting out of 4x4 on pavement. Go straight on gravel/dirt/snow, shift from full-time 4x4 to part time 4x4...wait a sec for the part-time light to go on (full-time light to go out), then shift to 2wd...let off of gas, then gently back on (might take a few times). This allows the transfer case to "unbind and the mechanism to work.

Just my $0.02...always works for me and seems easier on parts than "full throttle in reverse".