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| Why is there a series diode with a halogen bulb? |
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| Jeroen3:
In the process of investigating the possibilities of increasing the light in the trunk of my Honda, I pulled the lighting socket. I've bought an exact copy of this unit, to sacrifice as connector for the LED's I'm intending to mount in the trunk. However, something got my attention, and I can't think of a reason for it being there. Why is there a series diode with the small 5W halogen bulb? |
| james_s:
It's common with mains powered halogen lamps to drop the voltage enabling a shorter thicker filament. For an automotive light though I suspect it may be part of a multiplexing scheme with the various door switches and dome lights. |
| soldar:
It could be that they are using a standard 12 V bulb and the voltage drop in the diode protects it somewhat from the car's higher voltage. |
| RoGeorge:
Is it possible to unplug only the bulb from the whole connector&diode assembly? If yes, then my guess is the diode is there to protect a LED bulb against reverse voltages in case one decides to replace the incandescent light bulb with LEDs. Some LEDs are very sensitive to reverse voltage. Just a guess. |
| Jeroen3:
It's behind a 7.5A fuse branched directly from the 100A. It's low side switched by the trunk door switch. The low side does share some controller input to detect the door is open. Voltage drop wouldn't make sense, since this is the only light I could find that uses a diode. The ceiling lights for example, do not. The LED replacement could make sense. But none of non-indicator lights are LED in this 2009 model. |
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