norcal_jeep

recently fell into a 93 grand cherokee which i bought...i been told that it is stuck in 4wd....that its auto 4wd and it is sensing the different size tires in the front and rear and once i match the sizes on all 4 ..it will correct itself....thios is the 1st jeep i have owned...any feedback?

CodeXJ

Er... if it's always in 4wd you really should run the same tire sizes front/back. If you don't the transfer case will suffer binding and eventually break. AFAIK there is no 'auto 4wd' that will correct for different sized tires.

My brother has a '94 GC that is fulltime 4wd, I think it's the 'Quadra-Trac' transfer case. You may actually have something similiar, in which case it has no 2wd function. If it's a Quadra-Trac system, it should have a Quadra-Trac plate on the tailgate.

If it's -not- the Quadra-Trac, it's probably screwed up/broken because the idiot PO ran different sized tires front/rear, if you are very lucky it's just a broken linkage to the lever.

floydwall888

In for responses - never heard of this before. Sounds fishy...

norcal_jeep

Thanks for the replies. This mechanic said he was able to get it out but since the tire size differeneces it would go righ t back....today i am having 2 tires put on so all 4 will have same size...I guess i will see after work ...i couldnt even really tell it was usuing 4wd ..but i only have owned it 3 days
I dont see Quadra-Trac on the tailgate anywhere

CodeXJ

That doesn't make a lot of sense to me, as the 4wd functionality is not computer controlled in any way. You pull the lever, it goes into 4wd. Unless there is damage inside the transfer case and it's 'slipping' into 4wd for some reason. I may be wrong, however, I've not really screwed around with the innards of a case. I do know that running different sized tires is a fast track to a broken one, though.

Just curious, since I'm fairly certain the transfer case select lever isn't moving, why do you think its in 4wd? Is the dash light coming on, or is there some other reason?

Good luck!

norcal_jeep

Honestly i could not tell it was in 4WD...a mechanic who checked out the vehicle told me this...so it sounds like the transfer case is maybe broken....since this doesnt sound right to some of you maybe i need to question him more...its not like he is trying to run up a bill or anything...no there is no dash light on at all

CodeXJ

Then I'd be curious as to why he says it's in 4wd, since a dash light should come on.

If it's because the front driveshaft is spinning while driving, you need to hit him upside the head with a bat and take your jeep to someone who's not a 'freaking idiot'. The only -real- way to verify it's in 4wd would be to jack the vehicle up on all 4 corners, get in, and put it in gear. If the front tires turn as fast as the rear tires, it's in 4wd.

GreenClassic

If it's full-time 4wd, I don't think there would be a light saying it's in 4wd. There is no 2wd option on full-time 4x4 Grand Cherokees.

CodeXJ

I'm not sure, never been in a Full Time equipped vehicle other than my brothers, which is the Quadra-Trac unit that doesn't have a 2WD option. I would assume that a vehicle with a 2WD option would have a 4WD indicator when in 4WD mode, though.

GreenClassic

Yes, part-time 4x4 Jeeps have a 4x4 indicator light. But if it's always in 4x4, why would you need an indicator light?

CodeXJ

The Grand Cherokee only had one fully full time unit, the Quadra-Trac, which he doesn't have badging for and doesn't support 2wd operation to begin with, so why would the mechanic be trying to get it into 2wd mode?

That leaves him with either the NP231J or NP242J. The 231 is a part time unit only, the 242 provides full or part-time operation as well as a 2wd mode. I would suspect either of these two cases to have an indicator light, since they support 2wd operation and either 4wd part time only or part/full time.

Willys55

My 93 is full time 4wd, it has NO quadra trac label on it anywhere, and there is no 4x4 light because there is no reseaon for it. Other than that it sounds like you need to find another repair shop and you need to purchase a repair manual and learn a little about your ride

CodeXJ

Really? Well, guess I was wrong. Would have assumed they'd have an indicator light if the transfer case supported 2wd operation. But I guess not. From my understanding the only transfer case that didn't was the quadra-trac system.

Still curious, then, as to why the mechanic thinks it's in 4wd. Hope he's not thinking that because the front driveshaft turns when driving...

GreenClassic

Aren't all 4x4 ZJs full-time?

CodeXJ

I don't believe so, all the information I've found points to ZJs having the following 4x4 systems:

• Command-Trac (1993-95) w/ NP231. Part Time System with 2wd.
• Selec-Trac (1995-04) w/ NP242. Part/Full Time System with 2wd.
• Quadra-Trac (1993-98) w/ NP249. Full Time System without 2wd.