Until recently, vehicle four-wheel drive systems used manual locking hubs. To shift from two-wheel drive to four-wheel drive you had to stop the vehicle and engage the hub lock selector knobs on the front wheels. Today, the operation can be accomplished automatically with a button. Problems with locking front hubs can be related to the order of events, locking and not unlocking. These kinds of problems can be corrected by following some troubleshooting steps.
Turn the locking front hubs selector knob the correct way if the hubs won't lock. This will be marked on the knob and is usually clockwise. Look for an arrows and the labels "Lock" and "Free" or similar. Turn the knob in the "Lock" direction while the vehicle is stationary. Don't attempt it when the vehicle is moving.
Perform the hub locking in the correct order if you still have problems. Lock the hubs, then move the transfer case lever to the "4 High" or "4 Low" position. The hubs must be locked when in any four-wheel drive position, and both hubs must be locked. For example, the left and right manual locking hubs must not be set to opposite positions so one is locked and one free. Both must be "Free" or "Locked." Shift out of four-wheel drive if the front hubs are in the "Free" position. You can't drive a vehicle with free hubs in four-wheel drive.
Disengage automatic locking front hubs by reversing the vehicle. Stop the vehicle and press the "2WD" or similarly labeled button. Place the vehicle into reverse and reverse for a few yards. This will unlock the hubs, performing the same job that turning the hub selector does on manual hubs.
Unlock the front hubs and exit four-wheel drive by following the steps above if you encounter unusual drive-train noises when driving on dry pavement. Four-wheel drive and locked hubs are designed to be used on slippery surfaces only.
