Although I have not used these types of bulbs directly, I have heard stories of the "bulb-out" monitoring system (the "lamp out" light in the instrument cluster) becoming illuminated because of the significantly lower power usage of these new-generation bulbs. The bulb monitoring system uses a voltage measurement to determine whether there is a bulb out or not.Hi all, if you recall I this 500E had the boot lamp removed when I bought it. This is because of the Eco Junk wiring in the boot had welded itself together thus bypassing the switch permanently. I am re-making a new loom for the bootlid which will correct this issue.
However, I also noticed the inside of the lamp holder was burned inside. I have seen this on a junker car too on Saturday so it seems that the Festoon bulb, if left on could potentially be a fire hazard.
So I bought these bulbs to try them out
5x Festoon 42mm 264 8 LED 10x42 C10W Interior Car Light Bulb Ceailing Dome Lamp | eBay
They work great- plus on testing the current draw they only use 10% of the ‘stock’ bulbs current draw and give better light- being LED. More importantly they also stay 100% cool to the touch during operation unlike the original festoon bulbs. So I will now check the other interior courtesy festoon bulbs sizes and upgrade them all including the ones in the doors.
The other advantage is; should a bulb be left on accidently over night (such as the rear interior lamp) it will not kill the Battery at the 0.03A LED current draw and the risk of a fire due to the ageing fabrics / lamp holders exposed to heat is thus eliminated entirely.
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Would be good to try (and for any other folks using these bulbs to report if they are experiencing issues) these bulbs and let us know how they work, and if they trip the bulb monitoring. The bulb monitoring is mainly concerned with the exterior lamps -- headlights, turn signals, side markers, driving & fog lamps, and license plate lights.
I do know (from experience) that the bulb-monitoring system is not tripped by one of the small "city lights" being burned out or not illuminating (the small, dim bulbs in the "Euro" headlamps).
Cheers,
Gerry


































