I have a JD 4020 that is draing the battery. I have put a test light on the ground post and cable so there is a current there. Where should i start looking? How do i check to see if it is the alt. or the voltage regulator? It is a later model diesel. All i have is a test light for testing. i know i should have a voltage meter. if i need one i can probly find one. Thanks guys.