[peraklo]

Started a few days ago... when i open the doors, the light underneath starts flickering after about 30 seconds, first almost un-noticable, then more and more, untill its like a broken stroboscope. If i open just the drivers door, the passanger door LED is ok most of the time, but sometimes it starts flickering too. Does the same if the car is on or off, pushing various buttons (like reading lights, radio, etc), pushing the throttle...

Everything worked fine up to about mentioned few days ago. All other LEDs (rest of the interior, licence plates, trunk) work fine.

Where should i start with diagnosis?

[Jeff@TopGearSolutions]

The contacts to the LED are either loose or corroded. Inspect/Clean.

[peraklo]

since none other than door lights are flickering, i will do the check...

but if they are connected properly on the LED side, where would i search the other side of the cables?

[peraklo]

Ok, so i pulled out the lights from the Doors. Checked the connection, tightened the contacts grip, scratched the contacts with a screwdriver to rule out oxidation.. still flickering. And still, only the front Doors.

Might be a contact on the other side of those cables. My question, where do the wires from the Doors end up? Somewhere under the Hood? Fuse box? Anyone got schematics of the interior lighting with location of the parts?

Maybe worth mentioning that when i pulled out one of them, the other continued flickering Like there were no changes on the circuit. And given that they behave the same, and at the same time, im guessing they are in the same circuit.

Edit: googling is guiding me towards FRM. Seems like its time for me to start digging into the car instead od just driving it

Edit2: sometimes, i get a warning on my iDrive that one licence plate light is out. But its isnt...

[Jeff@TopGearSolutions]

9 out of 10 problems are dirty contacts.

If it's not the contacts and it's not the LED themselves then it could be a loose wire.

Not really much past that I'd know about. FRM is possible but I honestly wouldn't know.

[peraklo]

To reply myself, and all intetested...

I replaced LEDs on the Doors with regular cheapo T10 bulbs. No flickering whatsoever. Just crappy weak yelow light.

Could it just be that BOTH of the LED bulbs bit the dust at the same time? Or maybe it is some sort of Voltage stabilizer or something, that failed to properly Lower the 12V ?

Seems a bit unrealistic, i think that Voltage regulation happens on the LED itself (it has a few SMD elements on it).

I guess i Will have to purchase replacement LEDs, and see if the problem persists with new ones.

[matteblue3er]

LEDs do not regulate themselves. They need a circuit to control the current draw or they will burn themselves out. Without some kind of current limiting device, the LEDs will go into "thermal runaway."

For the door handle LEDs, I cannot image the need for a constant current driver. It's too cost prohibitive.

They are most likely limited with a simple resistor circuit. While this is cheap, it has it drawbacks. The main draw back is that you need stable voltage. As voltage increases, so will current draw and vice versa. Whereas with a constant current device will keep current stable regardless of voltage input (but it needs to stay above the minimum input voltage depending on driver type).

If you have a 4 door and the other doors do not flicker, I'd measure voltage and compare to the faulty doors. If you see a deviation, FRM might be damaged or maybe wiring could be shorted somewhere.

You can also try powering the LEDs from an external source. I'd start at 5v. Most likely the voltage is stepped down from 12v via PWM. Remember in a resistor setup, more voltage = more current.