Originally Posted by fuddyduddy121
That must be a high powered lamp, like a halogen trunk lamp. Helps you see the bodies better.
I think the trunk light is something like a plain old 1156, but if he'* got the test light jumpering the gap between battery and cable, the test light must be in series with everything downstream from it, including the trunk lamp bulb. When all the downstream circuits are basically opening up multiple ground paths for the test light to use, it'll come on at full brightness. If the trunk is then closed, so the trunk light circuit is cut, all that should remain would be memory circuits, keep-alive stuff in various processors, etc., none of which should be a high-current ground path.
So what I'm saying in all this rambling is that a low-level test light should be normal; one that'* blazing away at full brightness has probably found a ground path that shouldn't be there. (e.g. Power antenna running endlessly, automatic level control trying to fire up the air pump, that kind of thing.)