my 1989 jeep won't go into 4 x 4?

Question

if i put into 4x4 the front axle will spin but the front tires will not and the 4x4 light does not come on

Answer 1

On the passenger side, on the diff near the wheel is a round disk shapped thing with 3 hoses attached. This is the Central Axle Disconnect motor (CAD). If this thing doesn't work the jeep won't go into 4WD. The hoses are carrying vacuum.

To check: gently pry off the connections to the CAD (watch out the nipples tend to rust off). Start the engine and put it into 4HI.

Check for vacuum at the double hose. If none the hose is broken somewhere. If yes put the truck in 2HI and check the single hose. If no vacuum you have a broken line. if yes you have a defective CAD motor.

In any case I'd recommend you replace the entire system with a Posi-lock (look it up on the net). It replaces the entire CAD with a manual cable the you control from inside. The price is usually equal or slightly more expensive than whart the dealer will charge for a new shift motor.

Answer 2

If the front drive shaft spins, the transmission and the transfer case are okay. Check the front diff, the half shafts and the hubs.

Answer 3

Probably one of your hubs is not locking. I am assuming you have automatic locking hubs (which were pretty common by 1989) and after a while they begin to fail. If it were my Jeep I would go ahead and have it changed to manual locking hubs. You won't have any more problems with the maunual locking hubs and you always know if they are locked.

Answer 4

If it has lock in and out hubs turn it to the lock position if auto lock check to see if th bearings are lubed also check the fluid in the front pumkin to see if it is full.

Answer 5

you have a dead gearbox youre lucky it still moves