Well I soldered a wire on the one sending unit hooked yellow red and black red to the bigger sender and the two red blues to the smaller sender and the 4 wheel drive indicator is lit up for Lo and hi and goes out for 2 wheel with no change in the indicator for low or hi 4 wheel it probably doesn't change. . But the backup light is on all the time. I have to check tomorrow on the one smaller sender and see if the little ball is in it and then go from there.