It was working and then all of a sudden it wouldn't engage. The lights blink 4xlow and 4xhigh and every so often they go off. I once unplugged the battery cables and it worked but the next day it didn't work. When I try and turn the switch i can hear this clicking noise for a few seconds then the 4x4low/4x4high start to flash and will flash like that all day unless I keep the truck off for a day or so. Halp