This is the underhood light on my Ram 1500. It has a small weight in it, so when you open the hood, the weight moves, makes contact and the light comes on. Seems simple.
Here’s the problem, the light has come loose from the hood while driving (unknown to myself) and hangs downward. When it hangs down, the weight makes contact and turns on. This drains the battery. Two times now in the past year this has happened where I go to start my truck and the battery is completely dead. Open the hood and I see the light hanging down. Yesterday was the last day, unplugged it and never putting it back in.