4wd not engaging

well ever since i got the jeep the 4wd light never came on an i thought it was a bad wire or bulb so i read through some posts and figured i would check what the problem was. First I wanted to see if it was actually engaging in 4 wheel drive by engaging it backing up then forward making sure it locked in then I shut it off jacked up the frontend and tried to turn the front tires by hand. If i read correctly they shouldnt move well they DID. so i retried this 4 more times making sure i had it in right same thing. Ive had this jeep for a week so I havent needed 4wd I have only put it in on pavement testing it out. So after thinking for awhile i thought i would check the vacumn lines so I unplugged the lines at the front axle and the were clogged I tried sucking on them to see if i could get any pressure or flow an there plugged so I will probably replace them anything else might be the problem or anything I could do to test it out :dunno:

1988 BA-10 NP231 4.0L

TORX

TORX said:

... then I shut it off jacked up the frontend and tried to turn the front tires by hand. If i read correctly they shouldnt move well they DID. so i retried this 4 more times making sure i had it in right same thing.

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Did you jack up one front wheel, or the entire front axle? Did the wheel on the far side rotate in the opposite direction of the one you were turning?

Remember, the front axle has an open diff. With both wheels off the ground, the opposite wheel can spin without moving the driveshaft. If that's the way you tested it, your test was inconclusive. Put it 4WD, jack up just one front wheel, and then try to turn it.

Thanks I will get a new harness an that should hopefully fix it. I just replaced my CCV system last week so thats all good we will see what happens :thumbup:

TORX

Eagle you may be on to something Ill go try it right now :lecture:

No Effect

TORX

Well I took off the bottome 12" vacumn line an cleaned it all out till i could blow freely through it then reinstalled it cleaning the recieving tubes best i could. Gave it a test try nothing happend so now im thinking the vacumn acutator thing on the axle is clogged too! So ill try an clean that up tomorrow. My dad sugested repacking the hubs too so may give that a shot as well

TORX

Just cause you cleaned the vacuum line does not mean it seals against the shift motor. If it has an oily look and slilde on and off easily then it it not sealing. I still stand by my suggestion of buying a new hose, it the oil filter location that contributes to the failure.

There is a published procedure to check the operation of the shift motor. I am still not home but it should be in the factory manual OR prehaps www.alldatadiy.com will have it. A subscription to the site would be worth the $25 if it gives you the test procedure for the shift motor.

There are times you have to replace parts and this is one. I would of believed it either until I changed my shift motor harness. There was not much difference between the two but one the new one was installed my light came on!

I will buy a new harness for $10 you cant go wrong plus like you said martain currently there is an oily feel to it making it slide on an off with ease

TORX

Try one of the manuel lock setups to get rid of the vacum crap. They are ususally around 125 bucks. I know this is more than a new vacum hose, but the older the truck gets, the more leaks it will develope. Just an idea

Junk you have any links to that kit cuase ive been looking into it an thought my only options are warn or milemarker for $600+ if its less than 250 im sold cause i hate auto hubs they just plain out suck with all this vacumn crap

TORX

The vacum disco has nothing to do with hubs. The kits you are speaking of are hub conversons. I am talking about a cable that you pull in the cab of the jeep that slides the collar on the long side shaft, engaging the rest of the shaft to turn the wheel. I know that jcwhitney sells these things. The best I have seen is the Posilock. The price at whitney is a little steep for these things.

so rather than have a vacumn engage your 4wd you pull a cable if i am reading this right

TORX :anon:

That is how these things work. I have never used one, but known people who have. Never herd any negative thoughts on them. Some people play around with using it to disengage the front axle with a full time locker, kinda like a selectable locker. Do a search on the posilock, that is the best I have heard of. Just trying to help

Junk you have helped a ton thanks

TORX

I know www.4wheelers.com has them for $153, not the cheapest I have seen, but a sure link to buy one.