I have a 2014 (april) W212 E220 and have just swapped out my footwell lights for aftermarket LED replacements I got on eBay. They look good quality and well made - a direct replacement for the 4 footwell lamp units (complete units, not a bulb swap) and also the 2 boot / trunk lights. They are brighter and whiter than the original bulb type. However, I noticed they came on in a reduced brightness (still quite bright) when I unlock the central locking and brighten fully when a door is opened. BUT they stay on in the reduced brightness mode when I am driving at night, which is distracting. Are these faulty? Did the 'old style' lamps do the same but were so dim I didn't notice? Is there a fault? Is there an option somewhere that's been reset? Has anyone else experienced this? Can I get them to go off / much dimmer? Does this happen with LED bulb replacements rather than a complete unit? Help / advice gratefully received.

 

the lighting is designed to stay on at a dim level once the doors are closed and you’re driving. So the originals did stay on dim, you just didn’t realize it. I had also bought some aftermarket led replacements and had the same issue where they were way too bright while driving. So I returned them. I went and bought some Amber led light bulbs for the footwells which match the interior ambient lighting & the lighting behind all of the buttons. These are much dimmer while driving .

 

i also tried white LED’s with the same results and then switched to amber. I also discovered that the front footwell bulbs MUST be CANBUS compatible or they will blink. The rears and trunk lighting, no.

 

Thanks for the replies pb39374 & strife, much appreciated. Where did you get the replacement amber bulbs from? I've had a quick trawl of the interweb for W5W LED bulbs - I have found Philips do some good quality looking units in packs of two for around £12 ( $16 ) but these are 'white' so I'm guessing would have the same problem. The units I bought were complete replacements, so with a plastic 'lens' or lamp body with rows of LEDs fitted (and resister to comply with any cambus incompatibility). It would be great if someone produced a full replacement unit with white LEDs which only operated on normal/full voltage (c 12v) and a row of a few amber LEDs which came on at lower voltage (I'm assuming the dimming is produced by a drop in voltage?) or were on all the time. Thanks again for your replies.

 

I faced the exact same issue!! I solved it by making my own bulb that changes color and dimness.

Mercedes SLK R171 Footwell Accent Light Bulb | eBay

I made proper PCBs and sent to china for manufacturing. As I cannot order only 1 pc I am selling the rest. My car uses festoon light bulbs shaped a bit like this <=> . I thought the W212 used the same bulb.

Edit: my bad. the 211 used festoon bulbs. the 212 used the peanut (W5W) bulbs.

 

Thanks for this - as you said, the bulbs are different which is s shame. I ended up putting the original lamp holders back and purchasing some Philips 6000k W5W Ultinon Pro6000 replacement bulbs - these work fine, the 'dim' level is higher than the original lamps, but an acceptable level, so all OK now. I was impressed with your solution, and also saw your 'Soft Star' control unit, again a great idea. Only problem with the illuminated star in the UK is that you are not permitted to drive with it illuminated. The UK install kit comes on when you start the car, then goes off when you start to drive. The fixing kit is a nightmare to install otherwise I'd fit one. If your controller could be made to come on with ignition / lights, then go off after 30 seconds that would be cool for us brits! Thanks again for your reply - there is some great knowledge on here.

 

I thought Mercedes sorted out the illuminated star issue. The first generation OEM stars deactivated the light when you start driving (or turn on the ignition I cant remember). The newer OEMs always stayed lit and was very easy to wire. I guess that didnt apply there. Here in AU I did read the transport guidelines for additional "headlights" it mostly dealt with 4x4s with their massive external floodlights. The rule is that these lights have to be "distributed symetrically" from the centre. Its not illlegal to install more lights. But the star is in the center. Mathematically that fits the definition of "distributed symetrically from the centre" (I took a lot of maths to get my physics degree). In any case my first design of the controller did the soft start AND deactivation of the Star light after 30 sec. Maybe I should bring that back.

I havent actually seen an OEM star, but the aftermarket ones seem to be just as bright and have similar light distribution qualities. And they are really easy to install. Snap and twist and only 2 wires.

 

I dont know how much of a DIY guy you are, but you can build the colour changing light yourself. I gave the circuit diagram here:
https://www.slkworld.com/threads/pro.../#post-4743484
in my opinion, lighting the whole cabin with white LED (including the footwells) is nicer when you are leaving the car.

 

Something to keep in mind.
If our car still uses incandescent bulb for courtesy lightning and is dim-able by the car control, its dimming properties is for incandescent bulb and not LED.
LED has different minimum voltage and LED dimming method is not the same as incandescent bulb, so LED flickering can happen.
LED is a semiconductor and not simple filament like incandescent bulb.
If dimming is successful for the LED, LED being more efficient lumens per watt, it won't be as dim as oldie incandescent bulb.

The term CAN BUS compatible LED is wrong, its how seller makes buyer feel good buying LED replacement "bulbs".
The car computer, front SAM and rear SAM monitors current/load on the bulbs . It also send diagnostic signal to the bulbs to detect open circuit or blown bulb.
It can also detect short circuit or load higher than normal and will cut off power to those suspect bulbs.

Since LED needs very low power for the same brightness, the load is low and the car computer's declared that as a problem or open circuit.
LED manufacturers then install resistor/s to increase the load, or load cell...whatever... to make sure power consumption is within the watched perimeter
of the car computer.

So wasted power as heat is the victim of using a LED , if the car itself is designed for oldie incandescent bulb.
If LED seller is honest and explain how this cheat is done, buyers will be pissed. So they call it CAN BUS ready...LOL.

There is no CAN BUS involved towards the powering of bulbs or LED module. MB uses electronics to make sure that we owners will be warned when bulbs blown , more so like important one : the Brake Light and prevent fuse from being blown if short circuit or overload occurs. The switching is all transistor based. The CAN BUS is just the data channel to share the warning between computers on the car.

 

that's another sticky grade reference post that should be pined.