Hi All

I've just installed some LED Canbus friendly LED sidelights bulbs. They much better than the pee coloured OEM bulbs. My question is that, when turning the ignition on the bulbs flicker for a few seconds - my only assumption is that this is the Engine management system checking bulbs for integrity by sending small current through - causing the LED to flicker - the current not being enough to illuminate normal bulbs, but enough for the LEDs due to the lower current consumption.

Is this a plausible explanation? Any other ideas.

Ta

I feel very lonely - does no one fancy replying to me!!!!!!!! :'( :'( :'( :'( :'( :'(

Edited 23 December, 201015 yr by Tomdeswrig

I think you've hit the proverbial nail there.

On a normal filament bulb the current just tests continuity and isn't enough to illuminate.

Of course I could the talking out of my :moon:

Yes, its the Cold Diagnostics polling the filament to check for continuity. You can turn it off with VCDS.

Yes, its the Cold Diagnostics polling the filament to check for continuity. You can turn it off with VCDS.

I have that desactivated and still flicker along with my led DRL and led reverse lights.

I have that desactivated and still flicker along with my led DRL and led reverse lights.

Well, from what you describe above, its still active.

Don't forget you have to turn it off for each bulb circuit (parking, side, low-beam etc.) that you wish to deactivate.

Well, from what you describe above, its still active.

Don't forget you have to turn it off for each bulb circuit (parking, side, low-beam etc.) that you wish to deactivate.

After reading this I went out to see and it only turns off the rear license plate cold sensor thing.

There should be field for each bulb circuit - are you looking in the right place? Go through all the bytes. VAG wouldn't design the controller with cold diagnostics only on the number plate bulb.

Hi All

I've just installed some LED Canbus friendly LED sidelights bulbs. They much better than the pee coloured OEM bulbs. My question is that, when turning the ignition on the bulbs flicker for a few seconds - my only assumption is that this is the Engine management system checking bulbs for integrity by sending small current through - causing the LED to flicker - the current not being enough to illuminate normal bulbs, but enough for the LEDs due to the lower current consumption.

Is this a plausible explanation? Any other ideas.

Ta

LED'S are diodes after all, and are more responsive to any momentary voltage changes , filament lamps are not, so any system checks or CPU activity will be detected by LED's. I would think.