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Q: Can a blown bulb cause a short in the circuit resulting in a drained battery overnight ? Mercedes Benz

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Overnight my battery will be completely drained and I'm wondering if a blown license plate light can cause the circuit to short and draw current while the car is off

Hello - no, I don’t think it’s possible for a light bulb to cause a dead battery unless it’s left on overnight. Something else is going on here that’s draining your battery. This problem can be diagnosed by connecting an ammeter to the positive (red) battery cable, observe the current drain (likely less than 1 amp), then, one at a time, remove each fuse, check to see if the current drain has dropped to near 0, then reinsert the fuse. This process should identify the faulty circuit in most cases. The specific components on that circuit can then be checked for current drain problems. A professional mechanic, like YourMechanic, can come to your location, and perform this procedure for you, and replace/repair the failing component.

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