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#1 02-16-2012 16:38:29

emers
Lurker
Registered: 02-16-2012
Posts: 4

4 wheel drive

I have a 01 Grand Cherokee Laredo I6 with 3 different 4wheel drive settings.  For whatever reason my 4wheel full time went out this summer and i was left with the other 2 settings.  Now that its snowing, i have to use 4part time to get out of the snow but when i put it back in 2wheel, it won't go back.  It still drives like its in 4part time and i can't drive over 30mph and the steering pulls.  After shifting in and out a bunch of times, backing up in reverse, sooner or later it will shift back into 2wheel and drive fine.  What do I need to do to fix this, where can I go besides the factory, and what kind of cost am I looking at?

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02-16-2012 16:38:29

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Re: 4 wheel drive

#2 02-16-2012 16:42:04

howard
Helper
Registered: 10-05-2008
Posts: 24

Re: 4 wheel drive

I have an '86 that also does this, but not sure if the cause will prove
to be the same for your 2001. On the '86 there is a vacuum solenoid
(vacuum motor) that pushes the engage lever to engage the front wheel
drive clutch. These solenoids are very sensitive to the amount of
vacuum. If you have a small vacuum leak there may not be enough to do a
positive engage/disengage. This is especially a problem in the winter.
What I find helps temporarily is to shut off the heating system (which
is also vacuum operated if you have the AC option) and take my foot off
the gas either coasting or going down hill (thereby building up more
vacuum). This is a pain to do in the winter, especially in a storm
where you really need that heat on the windshield full time to avoid
freezing up. You can by a bypass mechanical system from
www.quadratec.com/default_*cherokee*.php
or find out where you are leaking from. You may have to replace the
vacuum solenoid if it is sticking from wear or if the diaphragm within
is leaking.

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#3 02-16-2012 17:53:07

drew
Helper
Registered: 10-22-2009
Posts: 22

Re: 4 wheel drive

Sounds like you have a NVG242 transfer case. The suggestion about a possible vacuum problem only applies to pre 90 Cherokees with a disconnect Dana 30 front axle. After 90 Cherokees did away with the problem prone disconnect front axle. Your 01 Grand Cherokee probably has the Command Trac transfer case with shift positions of 2W hi, 4w part time, 4w full time, Neutral, and 4w Low Part time. If you don't have any leaks from your transfer case indicating a lack of lubrication cause of self destruction, you may just have a shift linkage slop problem. The Z gate shifter Jeep used on the Cherokees is weak and clunky. It is difficult to feel the detent in the transfer-case through the handle. You might first try to readjust your transfer case shift linkage.
Shift the transfer case into 4low. Go underneath and loosen the adjustment clamp till it will slide on the rod. Make sure the lever on the transfer case is all the way back in the last detent. Go back inside and carefully pop the bezel cover off the transfer shifter. Place a 1/8" spacer between the shift lever and the back of the Z gate opening. (a 1/8 allen wrench works well for a spacer). Go back underneath and take all the slop out with the clamp towards the rear and tighten the clamp. Then shift the transfer case through all the detents. If you don't have enough travel to get 4 low or 2hi your linkage probably has too much slop. You may have to readjust the clamp position slightly to center the slop so you can get all the hi range positions. The 4wd shift fork is pushed out by a spring when you shift into 2wd so it may not come out of 4wd right away even after you shift back into 2wd. This is why you sometimes need to back up and go forward a time or two to release the front axle.
If adjusting the linkage doesn't correct your shifting troubles you have a more serious problem. Don't forget to check the oil level in the transfer case while you are under there. If the oil is low, smells burnt or has a silver color you may want to look for a replacement transfer case. New Process or New Venture Gear transfer cases are not very hard to work on nor are parts very expensive. If you do the work yourself a complete rebuild will only cost about $120 for a rebuild kit, $125 for a 242 chain and if the other parts are good that is it. The 242 has a inter axle differential so you can run 4wd full time. If yours has broken or the shift fork is worn maybe add another $80-120 in parts.

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#4 02-16-2012 17:55:07

howard
Helper
Registered: 10-05-2008
Posts: 24

Re: 4 wheel drive

Thanks for the input, but he has a different tcase than ours.  I would suggest making sure all tires are the same brand, tread wear and inflation.  The tcase can be forcibly shifted into 4WD, but the shifter will not force it out of gear.  There is only a little spring in it that does that.  If there is any pressure on the gears, it will not shift out.  The things I mentioned are almost mandatory for the NP 242 tcase.  Stopping and backing up will usually allow it to shift out.  Sometimes letting off the gas and or tapping the brake pedal are others.

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02-16-2012 17:55:07

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Re: 4 wheel drive

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