Led interior lamps flickering - shunt resistors needed?

[rcordran]

I've replaced the interior lamps with Osram 5W led replacements, but they flicker rather than dim after a delay when the car is locked. Has anyone noticed this and did you resolve the issue? I suspect adding a shunt resistor to increase the current draw might help, but thought I'd ask here before ordering some.

[warpc0il]

I had this with some branded leds.
Replaced with generic versions, mainly because I didn't like the blue/white light, but this also stopped the flickering.

I did suspect that the branded ones might have been fake but it's also possible that the replacements were CANBUS compatible ie they draw enough current to keep a bulb failure detection happy, and that might have fixed the flicker.

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[rcordran]

I Have exact same issue, and have had for several years. Just lived with it, but if you do figure it out let us know.

[Lemon]

sounds like an issue with the LED drivers.

[Delanor]

Sounds like an issue with the R3 as the only LED`s not replaced in my 40th are the indicators which I did do and they worked OK but then I found there is no safety warning if one of the LED`s packs up like a hyperflash on the Indicator relay so I left the bulbs in.

Apart from that all the interior LED`s performed the same.

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Del.

[untakenname]

I've got Osram's in mine and they flicker slightly when locking the car but it's not that noticeable compared with some cheaper ones I had in before which used to strobe wildly just before they turned off.
AFIAK the Phillips Ultinon LED's have pwm dimming support so shouldn't flicker but in my experience don't last that long even though they have a two year warranty they are a faff to RMA.

[Milos_Balunovic]

This is down to how the car dims the bulbs. Rather than vary the voltage it uses PWM (pulse width modulation) - effectively switching the bulbs off and on very quickly to achieve a dimmed effect. The longer they are on rather than off (the pulse width) the brighter they are. With an incandescent bulb this on/off effect is smoothed out as it takes the filament time to cool between pulses, resulting in a dimmer glow as the on pulse width decreases/off increases.

As LED bulbs react much more quickly to switching you can often see them flicker when the supply does this. Some are affected more than others - I fitted some very cheap ones from eBay years ago and they did have a slight flicker on dimming, but it looked pretty cool so I didn't mind. If you have some troublesome ones you might be able to smooth it out with a small value capacitor wired in parallel, but it's probably easier to just swap them for some that are less affected.

[Lemon]

I wonder if some of the LEDs we use at work could be fitted to a car... 500watt LED anyone?

[Milos_Balunovic]

I`m willing to give a couple of them a go in main beams please - I really hate dingy headlights!

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Del.

[wreeve]

You might be able to use a resistor and cap to make a RC filter to smooth the PWM


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[Milos_Balunovic]

I love it when you talk pulse & width!

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Del.

[PhilMac]

Sorry to be dim ;-) but can someone tell me what spec to search for the interior bulbs please ?
TIA

[Lemon]

the spec should be listed in the owners manual, just find LED bulbs that match the stated spec.

Be mindful though that LEDs don't dim in the same way that incandescent bulbs do which is why they flicker as them dim (and over time this can cause the drivers to fail so just flicker all the time)