LED's in Dome, won't turn off?
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short answer, they are poorly made.
long answer....I had that problem too with cheap festoon LEDs. what's happening is that the dome light circuit is negatively switched. what that means is that when the door is opened or you flip the switch on, one of the leads to the light goes to ground and completes the circuit. When the light is off both leads to the light will actually be given +12 volts and since there is no potential across this there is no light. BUT since the positive voltage is actually going across different paths in the wiring there is a very small difference in resistance in the wiring, this is giving off a very small voltage differential between the two leads.
now comes the problem with the cheap festoon leds. they typically overdrive the leds which is why they always burn out so fast. I've gotten anywhere from 1 to 3 months on those things before they start to burn out. When they overdrive the leds they using a too small resistor value, and the small amount of differential voltage in the dome light circuit is enough to give off a faint amount of light. If the resistor was higher then the voltage would not be enough to overcome it and light it up.
long answer....I had that problem too with cheap festoon LEDs. what's happening is that the dome light circuit is negatively switched. what that means is that when the door is opened or you flip the switch on, one of the leads to the light goes to ground and completes the circuit. When the light is off both leads to the light will actually be given +12 volts and since there is no potential across this there is no light. BUT since the positive voltage is actually going across different paths in the wiring there is a very small difference in resistance in the wiring, this is giving off a very small voltage differential between the two leads.
now comes the problem with the cheap festoon leds. they typically overdrive the leds which is why they always burn out so fast. I've gotten anywhere from 1 to 3 months on those things before they start to burn out. When they overdrive the leds they using a too small resistor value, and the small amount of differential voltage in the dome light circuit is enough to give off a faint amount of light. If the resistor was higher then the voltage would not be enough to overcome it and light it up.
Last edited by DHCrocks; 11-23-2006 at 09:14 AM.
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Why do I bother to DIY???
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www.velocityleds.com doesn't work It redirects to www.blazinleds.com...but still doesn't work.
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