How do you use a light tester on car battery to see if there is draw on current with ignition off?

Answer 1

with the vehicle off, remove the negative battery cable from the battery terminal. wait for half an hour. this will give your computer sufficient time to power down. this is important. there a multiple size test lights to indicate different levels of amperage. with a cheap one from a thrift store this will indicate any significant draw. hook the test light to the negative cable and the other end of the test light to the negative post. essentially, you have just completed the circuit that you previously broke when you took the cable off. if there is a draw on the system, the light will come on. if your light is very bright it is a generic indsication that the draw is a significant amount. you can pull one fuse at a time until the light goes out. when you find the right circuit, the ttest light will go out. then you can at least know that it is the taillights, or interior lights, ore whatever that fuse controls. keep in mind that if you open the door on your car, the interior light s will come on and the test light will light up bright. this is a normal draw. sometimes you have to depress the button thaqt turns the interior lights on when the door is opened. this is a basic and not in depth way to check for draws. this will not show parasitic draws. but hopefully this will get you started