Xenon light issue

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Seolio16

New Member
Joined
Oct 4, 2022
Messages
2
Location
Hampshire
Car
2001 CLK430 Convertible
My dad has an issue with the xenon’s on his 2004 CLK500 and we have tried the usual things that go wrong with xenon’s, with no luck.

The lights seem to intermittently go on and off, this was once in a while to begin and only on one light, but it has got worse over time. See video on link below.

It has had two new genuine MB ballasts (both replaced twice as MB wanted to check they weren’t a faulty batch), two new bulbs from MB and the main dealer spent quite some time investigating, checking wiring, etc, and even replacing a whole light unit at around £1k on a whim, and that still hasn’t resolved it. I am disinclined for my dad to spend more money at Mercedes without doing some investigation myself.

I have a decent amount of experience at fault finding and used to work in the industry, but I am yet to understand this lighting system, and have no diagrams currently as my copy of WIS stopped working! To be honest, I don’t have a workshop and it’s too cold to go investigating it on the driveway at the moment.

I just thought I would see if anybody has any ideas or has had similar experiences?

Thanks!

Video of light issue
 
Welcome.

And nice plate ;)

A 2004 car should have CANBUS, and isn't too old to tested with STAR (MB diagnostic computer) - has this been done?

My bet would be on an ECU going bad - possibly front SAM - maybe water (or oil) ingress into the SAM or the loom - has this been checked?
 
Welcome.

And nice plate ;)

A 2004 car should have CANBUS, and isn't too old to tested with STAR (MB diagnostic computer) - has this been done?

My bet would be on an ECU going bad - possibly front SAM - maybe water (or oil) ingress into the SAM or the loom - has this been checked?
Thanks!

I believe the star was put on according to the receipt as well as the loom, and I would hope that MB checked the SAM, but maybe not.

I wasn’t sure if it was controlled by the Front SAM or something else. But I am happy to check it, as we had issues with a SAM on our W164 a while back that caused a ton of issues. After a clean and reflow it hasn’t give any issues since.

Where is the Front SAM on the W209?
 
That’s a strange one.
I’d also check the voltage with the engine running is around 14.3 +/- .2 volts.
Pretty sure the front SAM is where the fusebox is on front o/s bulkhead.
There should be a plastic cover above it which channels the water off and is just clipped on and easily dislodged. Without it or if it is displaced, water can easily find its way into the fusebox/SAM.
 
I had a a C-Class of the same age with the same issue albeit affecting one side. The capsule/bulb was replaced first, then the ballast, and finally the headlamp - they didn’t expect the headlamp to fix it but they were out of ideas, and it did fix it.

I see that you’ve replaced the headlamp, was a brand new unit? Given that you have replaced everything associated with the headlamp then as @markjay suggests, I would be looking at the SAM next. Are there any other faults on the car?
 
Very odd indeed - The issue i had with mine did turn out to be the ballast, and it was only the left hand one..... I would investigate the SAM unit next as you seem to have already done all of the logical things already.

And..... i agree with the choice of number plate, very cool :cool:
 

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