I have a 1995 k3500 6.5 with no tail lites. Brake &turn work. Couldn't fine a tail lite fuse just an ILL. (Illumination) 10a fuse. Turned headlamp swt. on head lites on, instrument panel lites on. 10a ILL. fuse good but no voltage at fuse terminal. Also fuel gauge problem. Reads past full, dissconected connector at tank and needle pegs. 8ish Vdc at connector. Two wire unit , grd. good. Ohmed sender, 11.5 moved truck up and down and ohms bounced up and down. Any body have any detailed electrical schematics for lighting and sending unit circuits? Thanks Gus.