I have a 1989 K1500 and when the headlights are off, the blinkers work but are very dim as well as the taillights. When i turn the headlights on neither the blinkers, nor the taillights will work at all. Any advice is appreciated because I am lost when it comes to electrical problems, thanks.

 

Sounds like a bad ground. I would say one of your wires which in the engine compartment has rusted through.

Or headlight switch. BUt most likely ground wire.