W212 2012 model, left Xenon lamp out (not the Bulb or wiring)

[PaulOD]

Hi Folks

New issue but possibly related to my previous posts (Water Ingress), the Mrs hit a large puddle of water on Thursday night in torrential rain, not enough to cause concern just a big splash. Friday morning going to work she noticed the Auto light function warning coming on and then go off again all was well until she was returning from work on Friday night.
Firstly Auto light function warning came on and went out then head light out warning came on then the car began to chug (much like running out of fuel), so much so she had to pull over, at this point the engine Mgmt. light came on and the car went into low boost, the car drove 6 miles home in low boost with no chugging.
Today (Saturday) I cleared the codes and the car drives fine but the left head light was full of condensation and was not working(No Warning lights on the dash). On inspection the rear cover of the head light bulb housing was not on correctly so I thought its a bulb, water hit it in the splash and blew it. I dried out the lamp and one bulb later and still no head light, so I tried swapping the bulbs to the right side as it was working, the old bulb and the new one were both working when tried on the right side leaving me to think that the left lamp has a problem.
Is there an additional Xenon control unit that could be at fault for the lamp at least?
As always all feedback gratefully appreciated.

 

[Duffy3074]

You checked the ballast unit at the rear of the lamp?

 

[M80]

20,000 volt be careful how you check it.

That is if it's HID.

 

[Uncle Benz]

Sadly the control module sits on the underside of the lamp, with its electrical connections poking inside through the bottom face. It's the lowest point, where all the water that gets inside the lamp will ultimately collect. I'd wager that when you undo the screws and drop the unit off it will be full of water.

 

[Duffy3074]

You can access it by pulling the arch liner back.
Good bet it's the cause of your problems.

 

[star]

Sadly the control module sits on the underside of the lamp, with its electrical connections poking inside through the bottom face. It's the lowest point, where all the water that gets inside the lamp will ultimately collect. I'd wager that when you undo the screws and drop the unit off it will be full of water.

yep lots of water inside that lamp, just changing the ecu may last for a while until more water gets in and your new ecu is also toast.

 

[Uncle Benz]

If the open rear bulb cover was the source, you may get away with just the ballast module, but you must make sure the lamp is thoroughly dry. I'd recommend removing it and airing cupboard for a few days with every orifice opened. The lamp! Filthy minded kids!

 

[PaulOD]

Yep it's the ballast control unit and a bonus point for knowing it would be full of water, the lamp is dry now so I swapped the driver's side control unit and it worked.
Will I need to get the OEM replacement control unit coded by the dealer or is it plug and play?

 

[Duffy3074]

Plug and play, it’s just a ballast for the bulb

 

[Uncle Benz]

I’m afraid not. I think it needs coding

 

[star]

Did you find where the water ingress is coming from?

 

[Duffy3074]

I’m afraid not. I think it needs coding

https://www.ebay.co.uk/itm/LED-HEAD...-/183904898122?_trksid=p2349624.m46890.l49292

you sure??

 

[Uncle Benz]

https://www.ebay.co.uk/itm/LED-HEAD...-/183904898122?_trksid=p2349624.m46890.l49292

you sure??

I thought we were talking bi-xenon, not LED?

I've replaced the xenon units before, and the main beam didn't work until it was coded.

 

[Duffy3074]

My mistake
Had picked up on LED for some reason
If you’ve been in the same position and had to code it, I’ll bow to that experience

 

[PaulOD]

The silly prat that owns the car ,aka Me, drove into a flood a while back and both head lamps steamed up, then the same silly prat (me) removed the back lamp covers and left her in direct sun and they dried out lovely, it was my (prat) poor replacement of the left lamp covers that caused the water to get in this time, the passengers side cover was off and slide down behind the lamp, the drivers side was on correctly and has no issues (yet)

 

[Uncle Benz]

It may be worth putting the soaked module in a plastic bag with half a kilo of rice and popping in the airing cupboard for a few days. No guarantee, but I did this with a body control module from my neighbours Zafira recently and it saved a £300 unit.

 

[PaulOD]

Just tried the control unit after 2 days drying out and no joy, I have ordered an OEM control unit, should be here next week

 

[PaulOD]

Quick Update, I got an OEM "Hella" Ballast control unit and fitted it, The lamp now works but only as a Dip light (Previously it wouldn't work at all) the lamp does not increase its brightness when the head lamps are engaged.
Any thoughts on this folks, is it now in need of reprograming by the dealer? as I hear its not always successful with Xentry systems due to being off-line and unable to verify the via the Merc Database.

 

[star]

Good specialist ARE online.

 

[Uncle Benz]

I did warn you in post #13

decent independent can sort it out