There are a total of 5 detection switches on the transfer case. one is a neutral detection switch (operates briefly between high and low range). one is for 4wd detection, one is for 4wd operation, one is for center diff lock detection, and one is for center diff lock operation. basically, there is a switch that detects that you want it in 4wd, and then there is a switch that lets the ecu know that is successfully switched into 4wd. likewise with the center diff lock. there is a switch that detects when you push the stick into position to lock the center diff, and then there is a switch that lets you know when it actually successfully locks. just make sure all the plugs are plugged in correctly, (brown plug to brown plug, white to white, and black to black) all plugs are identical, and they will plug into each other in correctly (i.e. black to brown will fit, but will result in an incorrect circuit and the lights will act funny). if your t-case was working fine and then it just started acting up recently I would suspect that a switch came loose, a wire is cut or pinched, or if you had work done on it recently, the mechanic messed up something. when I had my t-case gears swapped out with 3.15's, the gear shop let one of the little steel balls that is supposed to sit right under each switch fall to the bottom of the case. when I changed my gear oil, it came out with it. I re-installed it accordingly. the switch it was missing from was the neutral detection switch, which you hardly even notice if it's working or not since your t-case is almost never in neutral. anyway, the switches are round with one wire coming out of them. you put a wrench on them to tighten or loosen them.