Well I fixed the 4wd on my 91' 6.2l k3500 but the floor T/C indicator light shows its in 4wd all the time (when its not). Could it be a bad switch somewhere?

Next, every once in awhile my tail lights decide not to work. My headlights and cab lights always work but my dually wheel well marker lmps and tail lights don't come on. I'm thinking its the dash mounted headlight switch. How about you guys/gals?