A Maryland bus driver completes the pre-trip inspection and notices a red emergency door light does not work. Why is this a serious issue?

1. If the emergency exit sign has a red emergency door light, the Maryland manual says it must work and be used at night or when outside lights are used
2. The light controls the engine oil pressure
3. The light is required only to decorate the exit sign
4. A nonworking light is acceptable if passengers know where the door is