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Discussion Starter · #1 ·
NP231 won\'t disengage 4H! Help!

I have a 94 YJ with the 2.5L and the AX-5 tranny and NP231 T-case. I was wheeling this past weekend. Once I got back on the pavement though, the 4H wouldn't disengage even though the lever is in 2H.There is a slight whine, but no grinding. There is no trouble moving the transfer lever to any setting and it engages 4L just fine, but will not release at 2H. I have checked the adjustment on the T-case linkage and it seems fine. Any help would be appreciated. thanks.

TXJeepr
 
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Discussion Starter · #2 ·
Re: NP231 won\'t disengage 4H! Help!

I have the same problem, the Jeep is with a mechie at the moment. I hope to find out more tomorrow what happened, it occured in similar circomstances at yours, but I didn't find out until after I repaired the the U-joint/yoke I broke and repaired (too enthusiatic on the throttle while climbing a sandy inclination!

I'll keep you informed

BlueJay
 
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Discussion Starter · #3 ·
Re: NP231 won\'t disengage 4H! Help!

Thanks, I would appreciate it.

TXJeepr
 
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Discussion Starter · #4 ·
Re: NP231 won\'t disengage 4H! Help!

That happened to my 97 once. It would shift into 2H, but it was still in 4H. So I drove in reverse for about a half of a block, I put it in first gear, accelerated slowly, and it went right back into 2H. I don't know why, but if you haven't tried it, it is at least worth a try. Best of luck to you.
Russ
 

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Re: NP231 won\'t disengage 4H! Help!

Check the front axle disconnect vent valve under the battery, and see if it is plugged. This won't allow the shift motor to pull back and release, and I believe that the switch for the light is controlled by the axle disconnect, and if it dosn't disconnect, the light will always be on. Also check that the vacuum harness is still hooked to the motor, you may have knocked it off while 4 wheelin.
 
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Discussion Starter · #6 ·
Re: NP231 won\'t disengage 4H! Help!

It is very possible the shift linkage has slipped or is bent. If it feels like 4-lo engages a tad bit earlier than it used to than thats it. There is a set screw holding the linkage. It can be loosened and the shift rod moved as needed. If all that is not the cause. Double check the front driveshaft to see if it is actually in four wheel drive. In other words, if the transfer case is in four wheel drive. It could also be the vacum(spelling I know) actuator on the axle.
 
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Discussion Starter · #7 ·
Re: NP231 won\'t disengage 4H! Help!

Background on my Jeep:
When engaging 4wd last time (ie before it wouldn't go back in to 2wd) it was very hard to shift it in to 4wd, but when it was there it shifted easily between 4H and 4L.
It is not the vacuum/light switch I had it on a hyd ramp and all four wheels were turning at the same time

The explanation I have with out actually knowing what causing it not to disengage 4wd is that the mode fork is not operating properly. The other fork selects H & L.

From the drawings it appears that this fork is on a rod but fixed with a locator screw(?), would it be possible that this screw has come undone and the rod is moving but the fork is just sitting there?

Again I hope to find out more today of the actual cause and any damage done (I must be stronger than I thought I was :)

BlueJay
 
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Discussion Starter · #8 ·
Re: NP231 won\'t disengage 4H! Help!

The transfer case disengaged today while decelerating up a hill. I also cleaned out the vacuum breaker valve that is located behind the battery (It was fairly crudded up.)and checked the adjustment on the linkage. I have not engaged 4H again as I am in Norman, Oklahoma w/ my grandparents and want to get home without risking getting it caught in 4H again. Luckily for me my grandfather has a well-outfitted shop. Thanks to everyone for the help and have a happy Turkey Day.

TXJeepr
 
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Discussion Starter · #9 ·
Re: NP231 won\'t disengage 4H! Help!

My friendly neighbourhood mechie had a look at the transfer case and it turns out it was the gear stick that not working poperly (I suppose from lack of use, OK I confess I don't go off-road that often! :( Anyway he saved me $$$$ if I would have gone to the Jeep dealer!

So a bit of greasing solved the problem!

Cheers

BlueJay
 

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Re: NP231 won\'t disengage 4H! Help!

/wwwthreads_images/icons/cool.gif BlueJay, are you smiling into the wind today?/wwwthreads_images/icons/crazy.gifKNOWING that your Jeep is OK?/wwwthreads_images/icons/cool.gif

CJDave
 
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Discussion Starter · #11 ·
Re: NP231 won\'t disengage 4H! Help!

CJDave,...

Just "survived" a 70knot (that is force 12, hurricane) last night, tends to make smiking a bit difficult if you want to keep your cheeks in place, AND got another one coming on my crew change day so delays probable as well!! but yes chuffed to bits that it is working again (MOAB here I come, does the snorkel allow the crossing of the Atlantic you thinK?) as they say overhere. I won't ever go back to those %%£*^£&^@@ they spoiled it for them selves.
Now I just would like to get my new Borla Header on before X-mas!

TTFN

BlueJay
 
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Discussion Starter · #12 ·
Re: NP231 won\'t disengage 4H! Help!

Hey Man,

Does your 94 YJ have Vacuum Acuators? If so, check those

Good Luck

Kevin Speicher
President
New England 4x4 Club
http://www.ne4x4.com
79 Jeep CJ-7
 

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Re: NP231 won\'t disengage 4H! Help!

/wwwthreads_images/icons/tongue.gif Yep, you could drive home if the snorkel had the optional extension tube. You know, speaking of snorkels, our neighbors bought a "Crate" Jeep back in about 1956. I was not too familiar with Jeeps at that age (13) but I was awed nonetheless that here was a "crated" army surplus Jeep.....you know the legends connected to that.....and I couldn't WAIT to see it. Well, it had the exhaust and intake extension tubes and was totally waterproof. He drove it through the river a few times just for kicks, and the water and sand just completely screwed the brakes. So that was it for swimming. Those guys also got a crated Dozer, army surplus (WWII) it came into our little town on the train in about 1952 or thereabouts. We all went down to see it, and they de-mothballed it right in the crate and backed that sucker out and down off the railside dock. They used the crate for a garage for YEARS. Both guys were lieutenants in WWII and had connections. Their whole ranch was run with army surplus. If they couldn't buy it surplus, they figured they didn't need it. In those days there was a lot of WWII stuff around. We had several GI 4X4s and 6X6's on our ranch. Love those two-lever transfer cases./wwwthreads_images/icons/crazy.gif 70K!!! Some little breeze! I'll bet THAT is; as they say....BRACING??? Heh heh./wwwthreads_images/icons/crazy.gif

CJDave
 
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Discussion Starter · #14 ·
Re: NP231 won\'t disengage 4H! Help!

Nah, that is not bracing when it gets up to 90 knts, thats bracing, impressive waves though, upto 15-20m (er 45 to 60ft).

Anyway saw a "triple" of flatfenders for sale this may (sorry don't know exactly what they were (ex WWII probably) in Scotland, one refurbished and road legal for $10k, She-whom-must-be-obeyed wouldn't let me buy since I already own two cars and have only one garage, she had a point! May be when I get to yor age ;) or when I win the lottery or,......

TTFN

BlueJay
 
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