On my '63 Chevrolet truck when I turn on the turn signal, my volt gauge needle jumps from 12-10 on the gauge. If I turn on the electric fan the volts drop to 8-10 on the gauge and stays there. NOW it gets interesting, I put a charging system tester on at the battery, with the truck running the charging system shows a charge of 14-15 volts. What do I need to do to trouble shoot these problems?
