Piston Slap: Going Ballast-ic on Bi-Xenons?

Sajeev Mehta
by Sajeev Mehta

Confused in South Bend writes:

Hi, Sajeev….

I am the owner of 2003 M-B C240 base, with the Bi-Xenon headlights. Recently, one of the headlights has developed an issue….in cold weather, it does not work.

Went to my German car specialist, who wasn’t so special on this issue. No problem, he said, replace the bulb. $160 later, still had the problem. OK, negotiated for him to give me a credit on the next fix.

Researched on the web, purchased a used Ballast. Mr. German car specialist looked at the part, scratched his head and said, “I don’t know what this part is.” Mercedes dealer says, spend about $900 for an entirely new headlight assembly.

I know that Mercedes engineers think money grows on trees….but $900 to fix a balky headlight? Come on…

I want to get this fixed….my question, is replacing the ballast the way to go? Or must I render to Stuttgart…..?

Sajeev answers:

When one HID headlight goes out, the ballast and/or the bulb is usually the problem. And I would never just buy a new HID bulb just to take a stab at the problem, especially when we know the quality of electronic components in German vehicles of this vintage. Who knows, maybe there’s a lighting control module mounted elsewhere that we non-German-techie people don’t know about! This is what specialty shops are supposed to do for us!

But, unfortunate diagnosis aside, I still think the smart money is on a bad ballast.

A visual inspection of the bulb is necessary, and the ballast is first tested by checking for power to the ballast itself. If you got nothing there, bigger problems away from the headlight assembly are in your future. If not, get the ballast tested and repaired/replaced. I am by no means a lighting guru, but from what I see via Googling, you can’t test a ballast with your garden variety multimeter. A specific tool is needed.

You made the classic mistake: buying a part and hoping for the best. Find someone who knows what they are doing to test and verify the actual problem. From the sound of it, you need a new German Specialist.

Send your queries to sajeev@thetruthaboutcars.com . Spare no details and ask for a speedy resolution if you’re in a hurry.

Sajeev Mehta
Sajeev Mehta

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  • Krhodes1 Krhodes1 on Mar 22, 2012

    And THIS is why my special-ordered BMW has plain old halogen headlights. HID = $1000 answer to a question that did not need asking. They aren't THAT much better.

  • Danwat1234 Danwat1234 on Mar 26, 2012

    Wow guys $1000 to replace HIDs? DDM tuning has a lifetime warranty on their HID kits, comes with a set of bixenon HIDs of your color temperature choice, ballasts, wiring harness. Costs about $70 USD. Pretty cheap if you ask me! I don't know where ya'll get the information that HIDs are expensive, they are not. I've had this HID kit on my car for over a year now and I have the lights on all the time when I'm driving during the day, works fine. Very bright. Bixenon; It has a little motor/solenoid that sucks the bulbs in when you want high beam. It doesn't use any blockers.

  • Mikey My late wife loved Mustangs ..We alway rented one while travelling . GM blood vetoed me purchasing one . 3 years after retirement bought an 08 rag top, followed by a 15 EB Hard top, In 18 i bought a low low mileage 05 GT rag with a stick.. The car had not been properly stored. That led to rodent issues !! Electrical nightmare. Lots of bucks !! The stick wasn't kind to my aging knees.. The 05 went to a long term dedicated Mustang guy. He loves it .. Today my garage tenant is a sweet 19 Camaro RS rag 6yl Auto. I just might take it out of hibernation this weekend. The Mustang will always hold a place in my heart.. Kudos to Ford for keeping it alive . I refuse to refer to the fake one by that storied name .
  • Ajla On the Mach-E, I still don't like it but my understanding is that it helps allow Ford to continue offering a V8 in the Mustang and F-150. Considering Dodge and Ram jumped off a cliff into 6-cylinder land there's probably some credibility to that story.
  • Ajla If I was Ford I would just troll Stellantis at all times.
  • Ronin It's one thing to stay tried and true to loyal past customers; you'll ensure a stream of revenue from your installed base- maybe every several years or so.It's another to attract net-new customers, who are dazzled by so many other attractive offerings that have more cargo capacity than that high-floored 4-Runner bed, and are not so scrunched in scrunchy front seats.Like with the FJ Cruiser: don't bother to update it, thereby saving money while explaining customers like it that way, all the way into oblivion. Not recognizing some customers like to actually have right rear visibility in their SUVs.
  • MaintenanceCosts It's not a Benz or a Jag / it's a 5-0 with a rag /And I don't wanna brag / but I could never be stag
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