DubVBenz

Was wondering if @konigstiger or anyone else might know of a bulletin or if this is expected behavior. I've had my 15 E400 for a little over 3 years and it now has 51K miles. Whenever the ambient temperature is above 65ish, the ILS LED cooling fans run for a full 30-60 minutes after every drive cycle (longer duration when higher temps). I thought this was normal until I mentioned it on thread with @S-Prihadi who indicated that seemed like a long time. I also compared this to two other W212 E350s with full ILS that are in my family (a 15 and 16 E350) and neither seem to run that long.
The fans are so aggressive that if I even open a door or unlock the car, they turn on proactively in anticipation of coming on (even if they have not yet).

Aside from the noise, this hasn't caused me any problems, but since these lamps are around 2-3K a piece, I'm wondering if I need to update coding or firmware proactively to prevent damage.

Is anyone aware of similar behavior, a workaround or TSB that relates to this?

CaliBenzDriver

I too got the same experience to be randomly greated by LED fans with cold lights Off.
I think these cooling fans are controlled by the F-SAM acting on internal sensors.
So far I don't have hands-on to deal with the internal module. I know that when you lock the car it shuts down the fans in a hury.

I wonder if the blown air source is filtered or if they the fan blades get plugged up with outdoor crud?

S-Prihadi

I can't yet find the INLET and EXHAUST port for these airflows at the headlight.
Me wondering the same too.....

DubVBenz

I'll see if locking it helps, it's always in my garage and unlocked when I notice it. Other times it'll be in a parking lot and I've long since walked away, but in my garage I can hear it as I go in and out to do things like bring out the garbage.

ygmn

Same here 2015 E400 Fancy headlights.
Park it, turn off engine, get out.
Shut door and go inside.
Read a book and go back into garage for a beer.
AND YES the dayum fan is still running...

My worry is it kills the battery
I mean how hot do these get
I was always told LED generate way less heat then other types of lights.
So what are we cooling? computer boards? OMG if we are... as underhood temps get crazy hot

And I looked in the manual and cannot find any reference but maybe I missed it as it is crazy thick book too.

KEY08

Locking the car shuts them down for me and mine is garaged like yours. If I don’t lock it they will run for awhile, shut down, then start running again whenever they feel like it. Once I noticed that I started locking it after every drive.

DubVBenz

I'm going to give that a shot... if that is the solution, I wonder what the logic behind that is.. Today or tomorrow should be a hot one, so I'll post back my results.

KEY08

Yeah, I don’t understand much of the Mercedes logic and these cars seem to like running programs even when sleeping. I could never get my Airmatic equipped models to stop farting either.

DubVBenz

Part of the reason it takes them so long to "sleep" and then they "wake up" at the slightest interaction (like door pull, approaching it,etc) is because we expect the electronics to be fully initialized and functional from the moment we turn them on. So by it waiting a long time to sleep, it prevents itself from having to restart everything every 2 minutes should you just be turning the car off temporarily. By starting everything up as soon as it thinks you might be getting ready to use it, it means you don't have to wait 30 seconds for the various digital and electronic gadgets that we are accustomed to to boot up. Because it's on battery, it can't be always on (mostly) like a computer can. Imagine if you had to boot up your car for 30-45 seconds each time you used it. Cars used to be analog, so as as soon as power was sent to the servos, motors,gauges, etc, they started working. Now every damned thing from the windows to the engine management is controlled by module of some sort.

It really makes you appreciate how they managed to achieve so many modern creature comforts in a W126 (everything was hard wired, engine management was very basic). It's also why much of that stuff still works on a W126 and W124 after all these years. Not a whole lot to go wrong.