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2007 Mercedes-Benz E550
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Discussion Starter · #1 ·
I have a 2007 E550 with code 615 (supposedly Bi-Xenon Adaptive Curvelight headlights). I say supposedly Bi-Xenon because switching to high beams activates halogens in the center position lights and I don't see an actual change via mechanical shutter on the HID lights. Anyway, that's neither here nor there. The problem I have is that the left low beam keeps shutting off. The symptoms are these:

With the headlight switch on either "Auto" or "On" both headlights will illuminate. The right side does the vertical and horizontal movement - down and then back up to level. The left light does not do any vertical and horizontal movement - it just points straight ahead. That's #1.

Symptom #2 is that after a minute or so of having the headlights on, the left will go dark and I'll get the message in the instrument panel of left low beam failure. If I switch the headlight switch to off and back to Auto or On, then the left headlight will come back on. I've noticed it seems to be willing to stay lit if I'm driving on the highway or at sustained RPMs. In traffic where I have to brake and slow down, letting the revs fall near idle, that seems to trigger the light to shut off. In other words, it seems maybe lower bus voltage (from brake lights being lit and minimized alternator charging due to low RPM) is a possible factor.

I have changed the headlight switch out with another used one and get the same results. I installed a brand new Philips 85410 XenStart HID bulb in the left headlamp and it still turned off after a minute.

My next step was going to be to buy a new ballast for the left. Then I thought rather than waste $150+, I would first swap the ballasts from left to right. I wish I had decided this when I had the car jacked up to change the oil last weekend but oh well.

(1) Are both ballasts fairly easily accessible by removing the front-most plastic under tray? If so, that's my next move. I'm not really keen on removing the front bumper if I don't have to.

(2) Is the failure of the left headlight to do the normal vertical and horizontal movement at startup a factor that suggests something other than a simple ballast? I.e., does that suggest maybe a HID control module that manages the illumination AND the movement may be the culprit?

I'm toying with the idea of getting an Xentry Star Diagnostic setup - is it sophisticated enough to pinpoint the real problem or would it just direct me to throw parts at it until it works right? The BMW diagnostic software ISTA+ is pretty good as it actually takes some control over the car for certain tests. But I haven't seen the MB one in action.

Thanks in advance. I'm anxious to get this fixed so I don't have to keep turning the switch off and on just to have working headlights.

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