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Part Time 4WD Issue

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Old 01-02-2015, 01:22 AM
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Default Part Time 4WD Issue

I drive an 89 jeep Cherokee auto. And when I put it in part time 4 on snowy/icy roads the 4wd will work up to a certain rpms than at like 2000 rpms the part time light goes off and kicks me back in 2. Then when I let off the gas it goes back in part time 4. It feels lime im engaging and disengaging as i accelerate/deaccelerate..I know not to use part time on dry roads with plenty of traction. If any one has had this problem or has seen it let.me know thanks!
Old 01-03-2015, 09:38 AM
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Originally Posted by jakeshredder
I drive an 89 jeep Cherokee auto. And when I put it in part time 4 on snowy/icy roads the 4wd will work up to a certain rpms than at like 2000 rpms the part time light goes off and kicks me back in 2. Then when I let off the gas it goes back in part time 4. It feels lime im engaging and disengaging as i accelerate/deaccelerate..I know not to use part time on dry roads with plenty of traction. If any one has had this problem or has seen it let.me know thanks!
Your front axle disconnect is releasing due to low vacuum most likely.

I do this to all of mine:

https://www.cherokeeforum.com/f51/fr...ss-91-a-38629/
Old 01-03-2015, 11:22 AM
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I did the free cad fix too. Its never let me down. I get a little axle noise but its not much more than my tires. I recommend it for sure
Old 01-03-2015, 02:34 PM
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Sounds easy! Ill give it a shot
Old 01-04-2015, 07:01 PM
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Originally Posted by cruiser54
Your front axle disconnect is releasing due to low vacuum most likely.

I do this to all of mine:

https://www.cherokeeforum.com/f51/fr...ss-91-a-38629/
hey cruiser, when you do this does it impact your mpg at all
?
Old 01-04-2015, 07:32 PM
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Originally Posted by jakeshredder
hey cruiser, when you do this does it impact your mpg at all
?
Heck no. The factory eliminated that troublesome crap in 91 anyway.


The big issue is that the CAD system only fails when you need it the most.

Kinda like when you don't realize your wiper blades need replacing til it rains....

I know somebody’s system works and he advocates keeping it stock, but my exposure to the failures is probably hundreds of times greater than his, as a result of being Service Manager at a Jeep dealership from 1980 through 1992, and being a current XJ and MJ owner.

CAD stinks. Every Jeep I work on with it, I eliminate it. Guess what I find in the process? 25 year old busted vac lines, bloated vac line connectors, bad vac reservoirs and piping. In other words, had the person gotten into a sticky situation and needed 4WD, they would have been screwed!!!

That's the tip of the iceberg. The factory went through 3 revisions of the shift fork also. The fork issue is non-existent if you just slide it over and leave it.
,
Old 01-04-2015, 07:43 PM
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In regards to the link cruiser posted in his first reply, I just did that to my Wrangler today without realizing it's such a common fix. There are several common ways to bypass, fix, or swap out the disconnect system, but that is definitely the easiest.


I had a Comanche with disconnect before, and had problems with both of them. Take care of it the way he said, and you'll never have to think about it again
Old 01-04-2015, 08:04 PM
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Originally Posted by cruiser54
Heck no. The factory eliminated that troublesome crap in 91 anyway.
Or 1990 since mine doesn't have it...or maybe it's because I have the full time option T-case. (?)
Old 01-04-2015, 08:07 PM
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Vac disco was used into model year '91. It's possible a previous owner already changed out your axle
Old 01-04-2015, 08:32 PM
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Originally Posted by '90Cherokee
Or 1990 since mine doesn't have it...or maybe it's because I have the full time option T-case. (?)
Full-time/NP242 had no disconnect.
Old 01-04-2015, 08:33 PM
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Interesting. That's good to know
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