Urgghh!! My drivers low beam is not working after replacing the bulb - Page 3 - Mercedes-Benz Forum
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post #21 of 26 (permalink) Old 04-29-2019, 09:50 AM
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Originally Posted by dlafever View Post
WOW, so many little things can add up to some major frustration! I can truly relate as so many times fixing Mercedes after someone else 'fixed' them is just sad and troubling.

Glad you are able to get the bumper to where you can remove the headlight assembly!

Also interesting about the shims, I don't recall shims on mine but I don't have the new new hotness of the facelifted model.

Thank you for taking the time to document your experience!
Dlafever , I can also relate here I am dealing with the same thing. Buying a used Mercedes and dealing with the careless previous owner's messy repairs or modifications. There is other things I had to deal with on my car but I will leave that for another topic. I want to say Thank you so much once again for helping me out with the part number I needed. You are truly a Hero
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post #22 of 26 (permalink) Old 04-29-2019, 02:01 PM Thread Starter
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Ok. Back to my original thread. Let me continue my detailed post so I can only help myself and not others.

So after you remove the headlight and get it on a flat work space lay it lens side down on a soft microfiber and inspect the rear. The headlight has three ballasts that control various functions; 1 a distinct rectangular shape and the other 2 are square. Since I'm not an electrical engineer, I have no way to confirm exactly which ballast controls which function except the rectangular ballast which repaired my low beam issue. As I stated in my prior posts, I decided to purchase all three replacement ballasts that were bench tested and with a replacement warranty. They all came with a refund policy minus shipping as well.

My goal was to replace all three since I already had the headlight on the table and there was no way to confirm any moisture that had gotten into the housing did not damage anything else. I would learn to regret this decision which I will detail shortly. I was able to remove a majority of the water from inside the housing and after inspecting the seal, there were 2 spots that looked to be compromised and a potential source of the leak. After I removed the outer headlight seal that seals any gaps between the light and body panels, I ran a thin beam of clear silicone along the entire perimeter of the lens. While that was drying, I started swapping out the ballasts.

For reference purposes, the part numbers for the ballasts left to right are as follows:

Rectangular Ballast = 1 307 329 240 00

Middle Square Ballast = A 216 820 03789

Outer Square Ballast = A 221 900 80 01


After I swapped the ballasts out and used a hairdryer to cure the silicone, I plugged in the wiring harness, disconnected my make shift clamp on the washer hose and re-installed the headlight. Because I wanted to test the full function of the light including the leveling motor I bolted the headlight in place to make it straight and reattached the left side of the bumper so I could plug in the left DLR. Reconnected the battery and started the engine. No warning lights so good news, but when I checked out the left headlight, the low beam was now working, but the led below the headlight was not. So one of the square replacement ballasts must be bad because the led worked fine before I swapped the parts out.

Unhooked everything again, including the friggin headlight washer hose. Pulled the headlight out again and decided to reinstall my old square ballasts. Got everything put back together and in the car. Turned on the lights and everything lights up properly. I don't know whether the active lighting system is functioning, but when I started the car, I did see the low beams ignite and the lights adjust down and then up. It was too late to take the car for a spin to check the cornering lights so I will post that info later.

In doing the research on this repair, the cheapest OEM headlights I could find with all three ballasts was about $650 plus shipping. I found all three ballasts for a total price under $300. The rectangular ballast only cost me $75 shipped so after returning the other 2 I'll recoup $200. The tube of clear silicone was $5 and gallon of windshield washer fluid was $3. Redoing this job twice? Priceless.


I don't know whether this makes a difference or if it just takes your car's computer a few minutes to scan the system and recognize new parts. When I started the engine after the second install using my push button, the low beam lights only ignited on, but did not move down and then up. When I used my key, I got what appeared to be an old message to replace the battery in the key fob (I never got this message before and the battery in the fob is brand new) and the low beams started to move. Either way, I thought I would provide this detail.

I plan on getting off the train tonight after it's pitch black so I will test the corning lights and high beam on function. With my exterior lights switch on "A" if you move the high beam lever towards the dash, your high beams should not turn on if the active lighting is working. Mine have been able to be turned on prior to this repair regardless of the setting so I knew the active lighting was not working.

Hope this helps someone down the road. I'll update this thread after I confirm the active lighting is working properly or if my system needs to be scanned with the MB Star scanner to reactivate that function.

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Last edited by tfvesquire; 04-29-2019 at 02:04 PM.
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post #23 of 26 (permalink) Old 05-06-2019, 08:55 AM Thread Starter
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Don't rely on used ballasts for your headlight repairs.

** UPDATE **

So, after posting my initial success removing the headlight and installing a "tested in good working condition" ballast for my low beam malfunction, last Wednesday I got a check low beam warning on the dash and the left low beam is out again. So word to the wise, purchase a new ballast or at least a refurbished one with a warranty. Surprisingly, the refurbs are not that much more than I bought the used one for. I received my replacement ballast super fast and by Friday night my low beam was working again.

I also visited my local MB dealer and purchased that fender liner/front bumper piece that closes the gap that was allowing high pressure soap and water to soak the headlight electronics. The piece was only $25 from the dealer. I will post the part info when I receive it. I also ordered another key fob since my car only came with one.

Once I am finished with my big trial in Kentucky I need to get my car in to be scanned to see why the active intelligent lighting system is not working. Hope everyone here in the Midwest is finally enjoying a little taste of spring.

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post #24 of 26 (permalink) Old 05-06-2019, 10:07 AM
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Glad things are getting sorted, due to your diligence of course! It's been spring here since ... well February, already looking forward to fall or November.
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post #25 of 26 (permalink) Old 06-13-2019, 01:08 PM Thread Starter
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Still sorting out the active headlights issue

So I just got back home after a 2 week trial in Kentucky. Won the trial, but now back to troubleshooting the new car and getting the active headlights working again. A little off topic, I was going to purchase a replacement front rim from a shop near me, but when I got there, the AMG rim turned out to be one of the earlier models with the wider spokes. The shop did quote me $200 to powdercoat and refinish my existing rim, so looks like I will end up going that route after I purchase a replacement tire.

While I was there, I told them about the headlight issue and the tech offered to scan my car for free to see what the problem was. Very nice of him so I had him check it out. The STAR diagnostic came up with the headlight ballast closest to the grill (part no. A 221 904 8001) was faulty and that is the one that controls the active headlights and cornering functions. He told me that once I install the replacement ballast I do not have to have it scanned again, but that the computer should recognize the new part and it should work again. Very cool I thought, so if a dealer or repair shop is telling you they have to charge you twice to have the car scanned, they may be hitting you up for an unneeded scan fee. Once I install and test the new ballast I will post my results accordingly.

I definitely missed my car while I was out of town. Pulling off the car cover and firing up the engine put a big smile on my face. With all this rain here in IL I keep having to go to the car wash. Should have bought the unlimited monthly wash pass....

Hope all is well with everyone.

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post #26 of 26 (permalink) Old 06-13-2019, 03:20 PM
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Sounds to me like a triple win - trial, headlamp, and wheel. Congratulations!

It brings to mind the luck of an acquaintance, aviation attorney Bruce Lampert. Bruce gave a lecture at my law school, after which I introduced myself. I had personally observed several of the incidents (or conditions surrounding the incidents) of several air crash cases he had tried - particularly, Continental 1713 at Denver (my wife and I were driving to Denver from Boulder, overlooking the airport, and saw that one go down); and United 585 at Colorado Springs (I heard the ferocious Chinook winds come down from the mountains as that plane tried to land; the crosswinds, which shook my house, were not the cause of the plane rolling inverted on short final; a malfunctioning rudder control unit was - but winds contributed). We discussed those, and the fact that I may have directed air strikes he flew from the USS Coral Sea when he was a Navy pilot (I was an Air Force Forward Air Controller, and directed many strikes flown from the Coral Sea).

He invited me to apply for a clerkship at his firm; I did. But on the day I showed for the interview, he was not there; his brother took the interview. Bruce had taken a vacation to Hawaii celebrating a victory, and of all things, he decided to take a side trip either to Sydney or Auckland, I don't recall which. He boarded United Flight 811, and was aboard when a cargo door latch failed, resulting in an explosive decompression that blew out the side of the aircraft and caused eight deaths. While the plane landed successfully (a minor miracle itself, given the structural damage), it was a truly frightful incident that has been highlighted on several TV programs.

Of course, he tried that case too.

I did not get the job. Bruce's brother asked what I thought of naming the pilots of Sioux City Flight 232 as defendants and going after them personally for damages. I told him that while it could be done as a matter of law, in my personal opinion everyone who survived that crash (which occurred after an engine explosion had cut all flight controls to the tail) owed their lives to the actions taken by those pilots - a point the defense was sure to make, and it could make the plaintiffs look bad going after them with greater emphasis than the FAA, the aircraft manufacturer, and the airline. I told him that when flying B-52s I used to practice approaches with simulated rudder and elevator failure - no one had ever successfully landed the Buf with such a condition. Two had crashed after failure of the hydraulic pumps powering those surfaces, and neither I nor the pilots I trained as a simulator instructor were able to do it in a flight simulator. I had once experienced loss of 3 of the 4 pumps, landing with very very slow controls running from a single small standby pump. I knew how dicey it was.

Wrong answer (for them, anyway). They were representing some of the plaintiffs, and definitely wanted to go after the pilots, heavily. Oh well. But I still hold the opinion I stated. And after graduation I went to work for a small aviation law and general civil practice in Florida.

Sorry for the diversion (luck after trials is what got me here) - back to the headlamps!! Looking forward to your final report on the ballast.


2013 S550

2010 S550
2005 S500 4-Matic
2000 S500
1978 450SL

Last edited by Skylaw; 06-13-2019 at 04:23 PM.
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