Any help on what I need to replace is appreciated.

Code reads "Control unit Actuation module LED exterior lighting, right front has a malfunction. The message is missing.

 

[edit] Look for part number 218900910380
#5 in illustration below. You may be able to swap left to right for testing purposes , though I believe the mounting is different.

Head light components

 

Thanks CR. I was looking for that part too reading another thread, but was unsure if that will fix it for good. It's pricey and I have to take off the whole damn front bumper and wheel well covers so hopefully said part will take care of this. I noticed that the active bulb on the affected headlight did not work when I turn the steering wheel to the right. Again, not sure if it is due to the module or I have a bad H7 bulb. Did you ever have to replace the H7 bulb on our cars?

 

When I replace this, do you think putting some silicone around the housing may prevent future water issues? It seems these go out a lot based on the amount of aftermarket sellers.

 

You shouldn't have to take off the front bumper. Just the inner fender wells.
See the pertinent section(s) on the WIS I have attached.

I would make sure to TEST the parts before purchasing. You'll have to resort to either swapping parts (ie left to right if possible) or testing with multimeter without XENTRY

There's a harness connector behind the inner fender well. as well as the the connectors going to the headlights and turn signals. I would check and make sure they are dry and no corrosion. Also make sure nothing is hitting the harness. Typically bad bulbs wont turn on or can be dim in some cases.


Good Luck

 

THANK YOU CR! You are a true gentleman!

 

Did the headlight fail on its own or did it occur after a wash?

 

after auto car wash

 

I edited the post above (#2) with a different part number. The old link was expired and kind of a mess. Looks like there are several part numbers too ☹️
I wouldn’t order anything until you have looked at what part number you have on your car.


Water is definitely getting in there somehow….
My guess is it’s pooling in that lower chamber where the connector goes into the control module. The connector doesn’t appear to be sealed. So sealing the connector around the outside with a bit of silicone may help. Possibly along with a well placed small drainage hole in the headlight housing(last choice). The two slots on the left (in red) of the module are also suspect as there is no drain hole on the bottom of that module. Once the water gets in there, it has nowhere to drain. But ideally you need to find where the water is getting in from. The headlight is clearly designed to be completely sealed.

If you can take some pictures of what that chamber area and the top of your module look like in your car it would probably help.
any signs of water etc…

 

Hopefully OP can post some pictures when he’s in there.
This seems to be one of those nagging problems that keeps coming up on the R231. It would be nice to isolate the cause and come up with a workaround or preventive measures that can be taken to avoid this.

 

For sure, planning on posting photos when I do the repair. I thought about putting some silicone around the seal of the module but I will see if that is plausible without removing the headlights (since its removal is not required to swap the module per instructions provided by CR).. If I can remove headlights with ease, I will try the silicone method.

Browsing Ebay, there are tons of aftermarket modules (non-MB/OEM) so probably a common issue with not only our SL (R231) but other models as well, like CLSs. Prices range from $75 bucks (knock offs) to +$300 (MB/OEM). As for the part #, I checked # 218-900-92-03 with an MB part site and it came up with 218-900-92-03-80, however, I could not find this # as most searches came back just as 218-900-92-03, so hopefully that's the correct part. We will know soon as I ordered one at a discount so it'll be available to me if I find that to be the issue.

PS: Recently, my local MB dealership had to come to my house to inspect my 2010 R350's for the national brake recall campaign. The tech brought his XENTRY scanner and did his thing. After, we had a conversation over a cold soda about cars and some career advise as he was a young chap. I asked him if he can hook me up and just do a quick scan of my SL headlights but he had to politely decline (due to boss, policy, etc.). BUT, he did mention that the symptoms I mentioned is common with some model's headlights including the SL. Oh well.

 

Greetings.

I finally got the time today to replace the Actuation LED module for my passenger side headlight, which triggered an error code few weeks ago. While it was satisfying to repair by DIY, if someone offered to do it for me for $200 bucks I would have gladly have accepted. I took my about 3 hours, excluding the extra time (described) below. Probably will take less time on my second attempt if needed.


It is a PAIN to remove the underlining cover and access the LED module. If you take the whole wheel off, it would be easier but I opted to just jack it up for more clearance. If you have a lift and remove the wheel, it would be a big time saver.

Upon removal of the module, I immediately noticed a green residue within the cable housing. Probably dried moisture of some kind. I knew I was getting somewhere with this repair. See photo.


On the electric panel side, I notice hard water residue surrounding the heat seat. See photos


From what I can see, moisture can enter through the headlamp unit down into the LED module by way of the harness and spread into the gaps between the heat sink and plastic cover - or less likely, through the seams of the module and the housing which is screwed down with 4 Torx screws (8mm). As a preventive measure, I squeezed premium clear silicone around the gap of the heat sink and the plastic cover. See photo. I can't recommend this hack to anyone at this time because I don't know what the end result will be - as time will only tell. However, silicone does not melt, so I don't have to worry about it melting into the electric board unit. I'm open to any comments if this hack should be avoided for any reason.


I did not have to erase the code as it erased by itself upon turning the ignition on.

Job well done!

PS> One regret is that I should have cleaned the original module and tested if it triggered an error code, but I did buy the new module at a discounted price so I don't feel too bad.

 

Ha, love it. 👍
Way to go hardcore wrenching, in the driveway even!

Glad you got it worked out. As you mentioned, it appears water may have pooled in there from the connector.
The problem with a sealed headlamp is water drainage in case of ingress. Can’t help but think a well placed drain hole wouldn’t help remedy this situation. Ideally water shouldn’t be entering that area. Looks like quite a bit got in ☹️

 

Thanks CR from the beginning of all this! Do you think my silicone hack may back fire later and cause other issues?

 

I doubt it. Those modules shouldn’t see the kind of temperatures that would melt silicone and that area presses up against the headlight housing seal, so ventilation shouldn’t be an issue either.

 

Sounds good CR! Have a great week mate.