Hotrodslim

Bought my daughter a 91 CK Larado 4 wheel worked when I bought it been working on it for about 3 months getting it ready for her Bday replacing hoses so forth all new brakes.. Got in it too test drive it in gaged 4high and nothing any ideas???

Hotrodslim

Help any ideas!!

caged

not sure but i think 91 still had the vacuum motor on the front differential. passenger side. those tend to rust out and leak, not letting the shift fork to engage.

you can replace the vacuum assisted shift motor, or you can install a cable to replace the vacuum line, it's called a posi-lok engagement cable, not to be confused as to a posi lock differential tho. it's only a cable to positively lock the front drive on a command trac 231 equipped jeep xj/yj.

or you can do as i did with my 90 and swap out the whole front axle for one from a limited that came with the selec-trac 242 equipped cherokee xj.

if you shift to 4 low range, does it give you low range but only rear wheel drive still?

Hotrodslim

Thank you very helpful full I didn't try the 4 low what if it does or doesn't??

Hotrodslim

[QUOTE="Hotrodslim;3189383"]Thank you very helpful i didn't try the 4 low what if it does or doesn't engage ??

caged

if you get 4 low but only the back wheels are moving, then chances are you have a vacuum actuator that is malfunctioning. and at least you will know the transfer case is operating properly.

if you get no movement, then possibly a misaligned linkage problem, then slightly moving the 4wd shifter may engage between gear indicators.

Hotrodslim

Thank you Cage I'm going to test that this weekend hope you have a great Xmas

andrewmp6

https://www.cherokeeforum.com/f51/fr...ss-91-a-38629/

cruiser54

Some 91s still had the vacuum actuator.

If it does, ditch it and be functional in less than a half hour and never worry about it again.
Here's why:

CAD STINKS


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 until 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 vacuum lines, bloated vacuum line connectors, bad vacuum reservoirs and piping, bad transfer case vacuum switches. 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.

See the link below for complete instructions. Takes less than 1/2 hour.

https://www.cherokeeforum.com/f51/fre...ss-91-a-38629/
,

Hotrodslim

Thanks love good advice and getting more than one how too check and fix and to eliminate it from happening again!!

Thank you all & Merry XMas!

andrewmp6

The cad was a good idea on paper,But in the real world its just something extra to go wrong when you need it the most.

cruiser54

Well stated.

And the mileage on non-CAD vehicles is the same as CAD equipped ones.

andrewmp6

Ford had its own dumb idea,They used vacuum hubs on the super duty trucks with the 4x4 switch.

Hotrodslim

yes they did worst thing ever they left me stranded in my driveway 2003 blizzard went from auto too manual real quick!!