Okay, I have a 1983 Diesel Isuzu Pup in fine shape. However, something has been draining the battery. It could be the generator is not generating like it oughter, but if I unhook the battery when I park the truck for any length of time (e few hours, overnight), then the battery is fine and is not even weak. So this is why I am thinking that something may be drawing electricity from the battery even while the truck is off. When I rehook-up the battery, by the way, some dohickey on the right side of the engine clicks, but I don't know exactly what the dohickey is or if it is normal that this click "on" should happen. How do I take one of these voltmeter/ampmeter thingees and find where electricity is flowing when the truck is off but the battery is connected?