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Discussion Starter · #1 ·
I purchased C5W replacement LED for my license plate lights. They are now exhibiting strange behavior -- after being on for a period of time they start to flicker and eventually go out. After a cooling off period they will re-light, flickering. With a longer cooling off, they will come back on normally.

The behavior is repeatable. I have no light-burned-out indication on the dash. I had no problems with the original, incandescent, bulbs.

I did notice that these things get HOT. I removed one when at flickering-temperature and was unable to touch the bulb/heatsink itself; a layer or two of paper was enough insulation though.

I bought bulbs advertised as CANBUS-safe on Amazon. 2 LED on each.

Did I just get bad ones? Or ones not designed for my application?
 

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I'll assume that by "CANbus safe" the seller means that it will not trigger a lamp-out warning. Most all systems do that by monitoring current through the bulb. Since LED's use way less power (= less current for a fixed voltage), the manufacturer has to add a resistor to the unit to make up the difference. That dropping resistor does nothing but bring up the current draw. That will create lots of heat, as does an incandescent bulb. [EE101 lesson over]

So my guess is that the heat from the dropping resistor is messing with the LED's ability to function. Yeah, I'd conclude they are just a bad design.
 

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You shouldn't need a canbus safe led for the license plate as it's not monitored for light out.
 

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Discussion Starter · #4 ·
You shouldn't need a canbus safe led for the license plate as it's not monitored for light out.
OK, I'll try a different set/different vendor and avoid the canbus-safe.
 

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On the 2011+ S60 it is monitored, but it will not trigger the bulb out light. It just gives a message to tech when he plugs the car into the computer.
 

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Discussion Starter · #6 ·
The new set I ordered mention "license plate light" rather than "dome light" in the description. I couldn't find anything that wasn't Canbus-safe with "license plate light" in the description.

The duty cycle (on/off times) are drasticly different for the two uses, maybe that matters.
 

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Discussion Starter · #7 ·
I got the new LED yesterday, installed, and drove with lights-on to work this morning. While the lenses are warm to the touch, the bulbs remained on (no flickering or shutting off as described above). I'll have to see how they behave with longer times.
 
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