So I have a 1986 c-10, I have never had any issues with it what so ever but when I tried to start it the other day and it had no power at all to anything. I have measured the voltage across the battery terminals to be 12.6 but if I go from the positive terminal to a body ground it only reads 8 volts. I have checked numerous wires in the cab and they all only read 8 volts as well. What would cause the battery terminal to termail to read normally but positive terminal to chassis ground only read 8 volts? I did the same measurements on my el camino and regardless of location of the ground either on the negative terminal or a chassis ground it always reads 12.6 volts