LED glowing?!?

HoMiPa · 08-19-2017, 08:17 AM

I have one LED bulb interior light that started glowing last night. I left if for awhile, then decided I didn't want to have my camper burn down with me & the dogs in it, so I removed it. None of them have ever done it before, and it wasn't warm at all. Any ideas? Should I just toss this bulb? It only started this last night, has never happened before. I'm on my phone, so I'm attaching a photo using Photogrid, that hopefully is reduced. Hopefully it will turn out ok.

Padgett · 08-19-2017, 08:27 AM

Only way I know for one to just start glowing is if it is getting some power. I'd check for that first.

**Larryjb** · 08-19-2017, 08:54 AM

Quick test: switch bulbs. If the bulb that glowed is bulb "A" in socket "A", swap it with a bulb from another socket "B". If bulb "A" glows in socket "B", than the bulb is faulty. If bulb "B" glows in socket "A", the socket is faulty.

HoMiPa · 08-19-2017, 09:01 AM

Quote:

Originally Posted by Larryjb

Quick test: switch bulbs.

Yes, I thought of that last night, but it was 12:45am, and I just couldn't be bothered. I stuck it back in this morning - but no glowing. Not sure if perhaps there is too much daylight to see the glow, or if it has corrected itself of whatever gremlin was there. I'll check after dark this evening.

**rickst29** · 08-19-2017, 09:29 AM

There's probably too much daylight to see the dim glow, but you can use a volt meter instead. In some lightbulb housings, the switch occurs on the white "Ground" wire. But most housings place the switch on the black "12V wire instead. Without looking, I will assume this switch to be present on the "black" wire.

There's some kind of short circuit between the "+12V" wire coming into the switch, and the switch "12V Hot wire" output into the lamp socket. When the switch is "OFF", the resistance should be infinite. If you can see un-insulated parts of these wires touching each other at any location, or sharing contact with any part of the housing, then wrap the open portions of the wires with electric tape, and separate them.

But more likely, the problem is inside the switch - when you turn the switch "off", a bit of dirt (or something else) remains connected between the two poles. I would remove the bulb and then flip the switch "off" / "on" about 50 times, hoping to loosen and remove any contact which remains present in the "off" position. Then put the bulb back in, or re-test resistance; if it still glows with the switch "off", then you need a new switch.

The Voltmeter "resistance test" test can also be done as a Voltage test: With the light bulb present, the Voltage Difference between "switch input" and "switch output" needs to be just as high as the difference between "switch input" and white "Ground". (All Voltage "lost" due to infinite resistance in the switch, none "lost" by power consumption in the light bulb.)