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I have a 2011 E350 CDI Blue Efficiency. It has the Intelligent Light(ing) System that automatically turns the high beam lights on/off. About a year ago I noticed a few times the lights wouldn't go to high beam. They'd be working properly and then would suddenly just stay on low beam. The high beams would come on if I held the lever back for passing beam, but not in the actual high beam position. At the time I thought maybe the windshield was dirty in front of the cameras because we were well into a 2 week road trip in the winter.
Lately I noticed it seems to be getting worse. I also noticed a couple of times that if I turned on the rear fog light and then off again, the ILS high beams would start to work again. That might be nothing but a coincidence. Tonight, they were working fine and then suddenly I had low beam only again. The rear fog trick didn't work, so maybe that was nothing anyway.
Lastly, I always leave the headlights switched to Auto, never manually turn them on/off.
Have you checked trouble codes? What happens if you switch headlights to ON and push lever forward, do they come on and stay on? if so it's likely a camera problem, needs to be reset or calibrated again, does the small auto headlight icon on the instrument cluster come on? could also possibly be a loose or corroded connection to the camera behind rear view mirror cover?
Last edited by pierrejoliat; Jan 30, 2025 at 08:44 AM.
I've been having a similar problem. I live in the mountains, so it gets very dark at night with lots of twists, turns, and wildlife. Not having the brights can make driving very interesting. Turn the car on at night, turn the auto brights on (I don't leave them on), and nothing happens. Logo is on the dash like it should be. After a few miles, they'll start working. If I wait a mile or so, then turn them off, I'll see the angle of the headlight drop a few degrees, and if I turn them right back on, it seems like they slowly climb again to the same point. If I push the switch the opposite way to flash the brights, they work just fine while it's held. It seems to have started happening to me when it started getting really cold this winter, so I figured it was temperature related. There are no codes, and the first shop I took it to didn't even hazard a guess. I'm dropping mine off at a Mercedes indie shop this morning, and I'm hoping he can figure it out. I'll report back.
Have you checked trouble codes? What happens if you switch headlights to ON and push lever forward, do they come on and stay on? if so it's likely a camera problem, needs to be reset or calibrated again, does the small auto headlight icon on the instrument cluster come on? could also possibly be a loose or corroded connection to the camera behind rear view mirror cover?
I haven't checked DTCs yet nor have I tried the lights in the ON position. I will do both. Yes, the Auto headlight icon does display every time the lever is forward for high beams.
Originally Posted by spectre6000
I've been having a similar problem. I live in the mountains, so it gets very dark at night with lots of twists, turns, and wildlife. Not having the brights can make driving very interesting. Turn the car on at night, turn the auto brights on (I don't leave them on), and nothing happens. Logo is on the dash like it should be. After a few miles, they'll start working. If I wait a mile or so, then turn them off, I'll see the angle of the headlight drop a few degrees, and if I turn them right back on, it seems like they slowly climb again to the same point. If I push the switch the opposite way to flash the brights, they work just fine while it's held. It seems to have started happening to me when it started getting really cold this winter, so I figured it was temperature related. There are no codes, and the first shop I took it to didn't even hazard a guess. I'm dropping mine off at a Mercedes indie shop this morning, and I'm hoping he can figure it out. I'll report back.
Sounds exactly like mine. The auto high beams don't work under 60 km/h which I'm sure is normal. The dropping and rising a few degrees is also normal dimming and back to high beam. I also hold the lever back in passing beam mode when the auto mode fails, but one can't do that forever. Temperature doesn't seem to be a factor for mine. Yes, please let us know what the indie shop says.
Isn't fixed yet, but while dropping it off, I went through the various maladies, and when we were talking about the headlights, the guy seemed very familiar with the issue. My head light lenses have some hazing on the inside per the below photo:
He said that's a sign that something is running too hot, and the motors are likely burned/burning out. My warranty has a carveout for headlights in some manner, but I don't think that extends to the existence of brights as in this case. Similarly, it excludes shocks, but will cover struts. We'll see how it pans out. Hopefully in my favor, but too soon to tell.
Isn't fixed yet, but while dropping it off, I went through the various maladies, and when we were talking about the headlights, the guy seemed very familiar with the issue. My head light lenses have some hazing on the inside per the below photo:
He said that's a sign that something is running too hot, and the motors are likely burned/burning out. My warranty has a carveout for headlights in some manner, but I don't think that extends to the existence of brights as in this case. Similarly, it excludes shocks, but will cover struts. We'll see how it pans out. Hopefully in my favor, but too soon to tell.
This burn in on the lens happens to all the Xenon lights, it is not indicative of overly high heat, Mercedes makes a kit to clean this off from the back, it is on the inside of the lens, you have a programming issue or your camera behind the rear view mirror has a bad connection or needs to be programmed/re-calibrated.
I haven't checked DTCs yet nor have I tried the lights in the ON position. I will do both. Yes, the Auto headlight icon does display every time the lever is forward for high beams.
Sounds exactly like mine. The auto high beams don't work under 60 km/h which I'm sure is normal. The dropping and rising a few degrees is also normal dimming and back to high beam. I also hold the lever back in passing beam mode when the auto mode fails, but one can't do that forever. Temperature doesn't seem to be a factor for mine. Yes, please let us know what the indie shop says.
Mine work over 20 MPH, Turn your headlight switch to on and then push the high beam lever, if they stay on high beam in that setting, its your camera that needs programming/ calibration or you have a loose or corroded connection behind the rear view mirror cover
Mine work over 20 MPH, Turn your headlight switch to on and then push the high beam lever, if they stay on high beam in that setting, its your camera that needs programming/ calibration or you have a loose or corroded connection behind the rear view mirror cover
Are you saying they won't start working until you get over 20mph? That's not a parameter I was paying special attention to, but I'm fairly certain I would have been going faster than that before they come on... Twisty, icy mountain roads at night with a car full of family will slow things down a bit though... Is this in a manual somewhere? For situations like mine, that can create some pretty gnarly situations... I guess under 20 mph will knock a deer down without putting it through the windshield though...
Are you saying they won't start working until you get over 20mph? That's not a parameter I was paying special attention to, but I'm fairly certain I would have been going faster than that before they come on... Twisty, icy mountain roads at night with a car full of family will slow things down a bit though... Is this in a manual somewhere? For situations like mine, that can create some pretty gnarly situations... I guess under 20 mph will knock a deer down without putting it through the windshield though...
Page 113 in the manual will give you the parameters of Auto highbeam, so yes, I'm saying exactly that
Page 113 in the manual will give you the parameters of Auto highbeam, so yes, I'm saying exactly that
So, I went out for a drive this evening for about 20 kms or so. This time my lights worked flawlessly - well, as flawlessly as usual. There have always been the odd false alarm that causes a momentary dimming to low beam, maybe the light reflecting off a sign just right to look like oncoming headlights. This often happens in the same places.
But, tonight, perfect. Regarding the speed factor - mine seem to NOT go to high beam until I reach 60 km/h (approx 35 mph). This is consistent, happens every time. I noticed tonight that they don't dim back to low beams by speed until I have slowed to about 25-30 km/h. Then they stay on low beam until the speed gets back to 60 km/h.
I also selected ON with the headlight switch (first time I did that with this car) while in town after the lights auto dimmed. They instantly came back to high beam. Like I said, they functioned perfectly. I will try this switching to ON the next time they fail to go to high beam when on Auto.
Finally, I saw in the menu that I can deactivate the Intelligent Lighting System. This is a last resort.
But, tonight, perfect. Regarding the speed factor - mine seem to NOT go to high beam until I reach 60 km/h (approx 35 mph).
I think that earlier ILS firmware had this higher activation threshold - can't quite remember where I heard that so it definitely could be wrong. (I don't even know where this threshold "lives", I just know my 2014 ILS equipped headlights are unable to receive any software updates.)
A $30 Openport 2.0 clone is absolutely worth it IMO. PM for (free) help getting Xentry if you can't get it yourself. As an aside, I am surprised that no "ILS inop" or similar messages are on the dash.
I think that earlier ILS firmware had this higher activation threshold - can't quite remember where I heard that so it definitely could be wrong. (I don't even know where this threshold "lives", I just know my 2014 ILS equipped headlights are unable to receive any software updates.)
A $30 Openport 2.0 clone is absolutely worth it IMO. PM for (free) help getting Xentry if you can't get it yourself. As an aside, I am surprised that no "ILS inop" or similar messages are on the dash.
Thank you. Yes, I may have to look at some way to get into the system for a bunch of stuff. I have been trying to get my Comand system updated. The maps are old, but the frustrating thing is that the Bluetooth connection for my phone is hit or miss. It always shows connected but half the time phone calls won't be through the system. I have read an update cures this, BUT the dealer refuses to do it for fear of bricking the system.
Update of sorts, but not really anything to update. The system has been flawless since I last wrote. Now I have to wonder if it can be environmental somehow. Last year it happened a LOT when driving through the Balkans in early March. There was some rain and more than usual drizzle and fog, but not always heavy.
The last time I was dealing with it this year here the weather was also a bit wet and occasionally drizzly - damp. The past few weeks have been colder with a very little bit of snow - in other words not really wet or damp.
When it failed the last time I confirmed that turning the headlight switch to ON instead of AUTO immediately gave me normal functioning of manual high beams. Even when faulted, they always do the correct down and back up alignment when I start the car (lights left in AUTO). Also, the cornering lights always work.
Update of sorts, but not really anything to update. The system has been flawless since I last wrote. Now I have to wonder if it can be environmental somehow. Last year it happened a LOT when driving through the Balkans in early March. There was some rain and more than usual drizzle and fog, but not always heavy.
The last time I was dealing with it this year here the weather was also a bit wet and occasionally drizzly - damp. The past few weeks have been colder with a very little bit of snow - in other words not really wet or damp.
When it failed the last time I confirmed that turning the headlight switch to ON instead of AUTO immediately gave me normal functioning of manual high beams. Even when faulted, they always do the correct down and back up alignment when I start the car (lights left in AUTO). Also, the cornering lights always work.
I'll report back if anything changes.
Could also be that the connector to the front camera got a better connection going over bumps in the road? I might check that connector undr the mirror cover if you have more issues
Could also be that the connector to the front camera got a better connection going over bumps in the road? I might check that connector undr the mirror cover if you have more issues
Picked my car up from the shop yesterday. Took a long time due to the warranty company/situation being generally difficult and unnecessarily complicated. Headlights were replaced. Supposedly they were tested and confirmed to have resolved the issue. I haven't had a chance to test the fix yet. Possibly this weekend.
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