hi pageda- that was my first thought here too. would be useful to check the alternator output at the alternator hot wire in the back too. should be 13.5-14.5v. to check the ground on the old american tanks you would jump a wire from the engine block or negative batt terminal to the body of the alternator (not the hot wire) and see if changes in output and the dash light changed. betting it is the ground wire. surmise the ground is the problem . should also check for corrosion and connections to the starter wires. thanks tons oldduke