Front hubs wont engage

check fuses and relays--- fluid levels ---transfer case --actuator movement

check to see if you have automatic hub locking. These units can be vacuum or electric operated and are prone to failure of the system

Someone will have to go under and check the linkage is working when the 4 wheel drive is fully engaged and not just moved to a neutral position.

Could be the servo on the front diff not activating. Could be a power prob or failed unit.

2002 chevy s10 4 door 4x4 4 wheel drive wont engage

Ok, this is probably going to sound greek if you have no automotive experiance, so here goes:

There are 2 possibilities I can think of at the moment depending on your 4wd system, however there are several things that can cause this

If you have a Push button 4wd (you push a button or turn a knob) the system engages using actuators or sylinoids meening you turn the 4wd on, the switch sends power to the selector option (high and low) and the 4wd light on the dash. the selector determines where the actuator/silenoid engages (either high or low) in the transfer case. However the actuator or silenoid can be faulty and yet the system will say 4wd is on because the switches still sending power to the 4x4 light

The next setup is the manual linkage set up, and given the year of your kia I doubt you have this setup However I am going to go through it anyway.

With a maual linkage setup you engage the trasfer case maualy using the 4wd shifter. Ironically on newer manual shift 4wd systems the dash light is still triggered electrically by location of the shifter not what is going on in the transfer case (Ah a flaw in the design) So if you linkage is loose/bent/damaged or somehow disconnected your 4wd wont engage but the light will still show that it is! Hope this helps

if you have access to a lift put somone in it sent it up
start it up put in 4wd low and check to se if the
output shaft is turning from the transfer case to the
front difirential if it's not turning odd's are transfer case problem if it is turning listen each front hub for
grinding noise if there is check the offending hub
by the way if you can't use a lift find some level paved
ground and use 4 STURDY jack stands to do tests
hope this helps any other ? just ask. good luck

That depends a lot on how your truck is equipped. GM uses several different 4 wheel systems including AWD, Part-Time 4WD, Full-Time 4WD, and ON-Demand AWD. Then there is another version used on some trucks that is a combination of 4WD and On Demand AWD. - it gets a little confusing but each system as slightly different charachteristics.

Genericly speaking, if you have the push-buttons on your dash that say "4-HI", "4-LO", and "2HI" and/or Auto-4WD , the transfer case has an electronicly-controlled stepper motor which shifts the transfer case into the selected mode. An electric solenoid/actuator then engages/disengages the front differential for 2-Wheel or 4-Wheel modes. One push of the button and it shifts the transfer case and engages the front differential.

That's much easier than the old days when you had to stop the truck, get out (Sometimes in the middle of a big mud hole) and lock the front hubs then get back in and play with the lever in the floor to get the transfer case to shift into the desired mode.

Front hubs need to be taken off and inspected for damage,
Replace as necessary.

I had the same problem with the shift on the fly push-button 4x4 on my 97 Suburban. GM Shop manual indicates that it could be due to an encoder error on the actuator motor. Try pulling the transfer case fuse to reset the transfer case control module. Wait at least one minute. Re-install fuse then re-try operation. Did it last week and that saved me a trip to the dealership and extensive troubleshooting.