there are 2 plugs on the transfer case. I forget which one it is but just unplug 1 at a time. Unplug the top one then start and check. if the service 4wd comes up. plug that one back in and unplug the other one and recheck. That is what i did and everything works fine. Before u do unplug and switches, make sure your transfer case is not leaking/empty because this will also cause the service 4wd to light up.