[red71cheyenne]

The gas guage is usually indicative of a bad sender or an open wire. Could be the ground on the dash harness is loose. As far as checking for amps, you need to check it the way the drawing is. Thru an open in the circuit. If you try to read voltage there, it won't read right. Read voltage across the line, like with the ground cable connected. Looks like your dash lights and gas guage might either be affected, or part of the problem. I know you said you headlight switch wasn't bad, but do you have a spare you can plug in to check it? Jeff.