What would cause the 4WD mode in my '91 Jeep Cherokee to quit working?

Question

The "4WD" indicator does not illuminate; however, when 4DW "low" is engaged, the vehicle appears to be operating at the appropriate low gear ratio - except that the front wheels do not turn. I took it to a mechanic who said that the transfer case appeared to be fine. Hubs, perhaps? How much of a pain in the rump would it be for me to repair this myself, considering that I am a mechanical idiot? Thanks in advance.

It has auto-locking hubs.

Answer 1

Wow, that's scary, the mechanic doesn't know? I'd get a second opinion. IIRC, this is a vacuum operated system. There should be a 4 hose vacuum switch on the transfer case and a two hose shift motor on the right front axle (which also controls the 4WD light). Let the vehicle idle (in 2WD), and remove both vacuum hoses from the front axle shift motor ( don't mix them up!). One should have good vacuum. Then shift it into 4WD, and the vacuum should switch to the other hose. If it does, the transfer case shift linkage and transfer case vacuum switch are OK. The problem is likely the shift motor in the front axle. If the vacuum doesn't switch hoses, the vacuum switch in the transfer case is defective, or there are internal transfer case problems. If there is NO vacuum at either hose, the transfer case switch could be bad, or there is no vacuum getting to the transfer case switch (broken vacuum hose). It's still also possible you have internal transfer case problems, but I would be willing to bet that either no vacuum is getting to the transfer case switch, or the switch itself is defective. If I can be of further assistance, let me know, but make sure you have a valid e-mail address!

Answer 2

Jeep Cherokee's have no locking hubs. They're always locked. The most simple solution to your problem is the light bulb burned out. If it acts as in 4wd then it is. You should also feel a handling and power difference most definitely in 4lo. Or it could be a loose wire to the bulb. If the 4wd seems to work fine and the mechanic said it was good I wouldn't worry about the light. Just look at the shifter. The front wheels don't turn a corner or don't provide power? If they don't provide power then you have a vaccum leak in your disconnect axle. Simple fix find the vaccum hose coming from the passanger side of the axle and replace it with a new one. Or get a posi-lock which is a cable operated version of the same thing.

Answer 3

I had that same thing happen in my '95 Chevy truck. It was an actuator in the front end. I replaced it with a Posi-Lock kit. I posted a link for Jeep Posi-Lock kit. I don't know if they have them for you jeep though. I think that if your not confident repairing it you need to find a trustworthy shop. Which that doesn't exsist where I live. You especially need to take it to a shop if your not sure of what it is. You should take it back to the mechanic and have him find the problem. Well good luck. I hope I helped at least a little bit.

Answer 4

I believe that the hubs on that jeep have a vacuum actuator. (A small diaphragm located on the front axle.) There should be a Small rubber hose that runs to it. any small crack would cause the hubs not to engage.

Answer 5

DOES IT HAVE AUTO HUBS.. IF IT DOES I WOULD RECOMMEND PUTTING IN MANUAL.. AS FOR COMPLICATED A LITTLE MORE MESSY THAN ANYTHING TYPICALLY A GOOD IDEA TO REPLACE WHEEL BEARINGS WHILE YOU ARE IN THERE AT THE MOST 10 BUCKS FOR PARTS PER WHEEL.. AS FOR HUBS GO TO WWW.PARTSAMERICA.COM TO SEE WHAT THEY WILL RUN U ,, WARN IS A GOOD BRAND U CAN TRUST.. BUY YOU A HAYNES MANUAL OR GET A SUBSCRIPTION TO ALLDATADIY.COM I THINK IT IS 25 DOLLARS FOR A YEAR.

Answer 6

do your hubs lock by themself? Or do you have to get out and lock them yourself?

Answer 7

lugnutz59 hit it just right go with his anawer