off-roader
Expedition Leader
It works on pavement however... all you do is put it into 4L and engage the locker via the switch. Check that your diff lock indicator is constantly lit. Make a slow turn (1-2mph) in either direction and you should hear the rear tires scraping on the pavement since they cannot turn at different speeds when locked. If you hear this, then it's an indication that the locker works. Come to a stop. Disengage the rear locker with the switch. The diff lock light should shut off. Try again to make a slow turn in either direction. The tires should sound normal and not like they're sliding across the pavement.
Also confirm that your 4wd center diff light shuts off indicating the Central Axle Disconnect has disconnected. if it flashes, then that's an indicator that the CAD is sticking. Usually this means the system needs to be cycled on/off a few to a dozen times. If it does not shut off after that then there is a possiblity you have a bigger issue there.
HTH.
Also confirm that your 4wd center diff light shuts off indicating the Central Axle Disconnect has disconnected. if it flashes, then that's an indicator that the CAD is sticking. Usually this means the system needs to be cycled on/off a few to a dozen times. If it does not shut off after that then there is a possiblity you have a bigger issue there.
HTH.