I have an 88 chevy full size truck. I am having electrical difficulties. When I brake, the light display for my heater dims. When I turn on my headlights, my tailights don't come on, and the turnsignals will come on and stay lit when I turn the signal. There are four wires going to the tail lights; dark green, light green, brown, and yellow. The light green, and yellow wires are left and right turn signal. The dark green is backup. The brown is from the head light dimmer switch. When I checked to see if a wire was grounded I found connectivity in the brown wire to ground, so I replaced the brown wire, still grounded. I need direction to what to do next please.