The Truth About Cars » headlight The Truth About Cars is dedicated to providing candid, unbiased automobile reviews and the latest in auto industry news. Wed, 16 Jul 2014 16:33:07 +0000 en-US hourly 1 The Truth About Cars is dedicated to providing candid, unbiased automobile reviews and the latest in auto industry news. The Truth About Cars no The Truth About Cars (The Truth About Cars) 2006-2009 The Truth About Cars The Truth About Cars is dedicated to providing candid, unbiased automobile reviews and the latest in auto industry news. The Truth About Cars » headlight Piston Slap: Affalterbach’s A-faltering Headlight! Thu, 01 Aug 2013 12:00:40 +0000 SLK32AMG_front1

Martin writes:

Hi Sajeev,

I’m writing you because I’ve searched and asked model-specific forums, and mechanics, to no avail. I have the last of the 1st Gen SLK AMGs. I love this car, and I’ve loved it since the first non-AMG launched in the late 90s. Overall, it’s well maintained – a trend which I continue – and I’ve had it for a few years. I have one major issue.

The Xenon headlights will blink out randomly – the issue is solved by flicking the lights completely off, and then back on…it almost always happens on my passenger side headlight, but I’ve seen it happen on the driver’s side as well though this is rare. It usually happens on a bump, or on impact of some kind, like a speed bump, braking, or closing the hood, and can occur every few minutes (usually in wet weather – thought doesn’t ALWAYS happen in wet weather) or not at all for several months (usually dry weather).

Mechanics have diagnosed it as anything ranging from a bad ballast (doesn’t make sense to me as ballasts either work or the don’t) to a faulty bulb. One mechanic put some kind of lubrication on the contacts with the bulb and the problem went away for several months – even in wet weather, but I’m not sure if this was a solution or coincidence. Due to two factors – higher incidence of occurrence in wet weather – and the presence of condensation in the passenger’s side bulb (the worst offender) – I think there’s a short somewhere. I’ve checked the wiring and it seems ok. No one can give me a convincing reason as to why I should just replace the whole headlight assembly (an expensive proposal) – and although I realize AMG cars are pricier to maintain and I don’t mind spending, I also don’t want to do it unnecessarily just to discover that it’s a short in some kind of control module or peripheral piece.

Have you ever heard of this? Looking forward to your input.

Sajeev answers:

Not an easy question, but luckily you want what’s best for the car. Which isn’t cheap for a German car of this era. I still have nightmares about attempting to fix anything on my Father’s former 1996 BMW 750iL…beautiful, glorious nightmares I tell you!

Proper Mercedes-Benz shop manuals for this car are a must…but first…give this a shot:

A problem this intermittent, normally happening on one side means there’s an easy diagnostic route: switch headlights (first) and ballasts (second, assuming there are two, so RTFM) between left and right headlights and see if the flickering pattern changes.  If so great…you probably found your offender.

If not…well…

I am somewhat confident that voltage irregularities in failing ballasts can cause this, but the bulbs themselves aren’t free from guilt.  I worry because you flick’d them off/on: hot re-strikes on many older HID bulbs is a big no-no.  BIIIIIG no-no, as I learned when converting the horrible headlights on my 1995 Mark VIII to the HIDs of the 1996 model: this shortens HID lifespan significantly.

If the HID bulbs are original, perhaps they need replacement after the hot re-striking and from age. Or maybe the ballasts are no longer up to par internally, perhaps a lighting specialist can load test them to verify. I doubt you have wiring problems, but who knows…I haven’t checked myself!

Who really knows how to arm-chair this query? What say you, Best and Brightest?


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


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Piston Slap: Going Ballast-ic on Bi-Xenons? Wed, 21 Mar 2012 11:35:35 +0000


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 . Spare no details and ask for a speedy resolution if you’re in a hurry.



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Piston Slap: Of HID-retrofit Hatred, Panther Love…PART II Wed, 11 Jan 2012 22:02:31 +0000

A TTAC lurker writes:

Sajeev, I’m local to Houston and greatly look forward to my daily lurk on TTAC. I just had to respond affirmatively to the latest piston slap about HID’s and Panthers.
I own 2 CV’s, an unmolested 2003 Sport:
…and a 2002 HPP with various mods/tune: you will note the projector headlights in the ’02. I couldn’t agree more with the comments about the cheap HID kits and resulting glare/distraction to other drivers. In my case I went the route of a complete E55 projector retrofit and new wiring harness for a proper and adjustable installation. I’ve included a complete DIY I had posted on under my now-sold PI moniker Blue95 for your reading pleasure! IMO the only way to install HID lighting. Has been installed for about 2 years, no operating issues at all and no problems with state inspection.

Sajeev answers:

First off: you are a hero for preserving a Panther (or any mildly historically relevant car, for that matter) and for doing a really impressive job in your HID conversion on Panther #2.  That said, it may not be to the letter of the law as your new headlight bucket hasn’t been approved by the DOT, but whatever. Best and Brightest, that’s for you to decide.

Second off: I think I saw your 2003 Sport at IKEA about 3 weeks ago, maybe on a Saturday.  You had me drooling as I walked in.  Thanks for that, it sure made the notion of buying press-board minimalist furniture far more enticing.

Third off: upgrading to projector style headlight assemblies makes the HID-hatred far less terrible.  Combine that with an OEM-style bulb rating (no blue/yellow/radioactive rated bulbs) and you are within spitting distance of what Dearborn put in that non-Panther thing they call a Taurus.  It was mentioned in the previous comments by “turbosaab” to the same effect: you will get away with a good projector assembly, conservative HIDs, and quality wiring and relays/ballasts.  I encourage everyone to read the PDF in your letter to see the extent of work necessary to do a “proper” HID retrofit on a car without projectors from the factory.

And lastly, have a look at another excellent post from the last Piston Slap that deserves the oxygen of publicity:

In our first installment, TTAC Commentator jco wrote:

There’s just no way you’ll get acceptable beam pattern and anything less than atrocious amounts of glare if you wire up an HID kit in halogen-designed open reflector housings….so the housing was designed to shape that type of light. And yes, I see junky HID kits in reflector housings all the time. it just looks cheap and wrong. there are usually huge hot spots at the top of the housing, specifically throwing glare at others. i don’t think there are any OEMs using HID in a non-projector housing.

I installed a well-made (it came with a wire harness with in-line fuses and directly plugged into my headlight harness. it takes the stress of the increased startup power away from the factory wiring) HID retro kit in my truck. But my truck already has projector housings for the low beams. though the lenses are not optimized for that type of bulb, they work about 90% as well a true OEM setup. and i spent time adjusting the level on the beams. i have driven another car in front of my truck at night and it’s not glare-y at all.

some people will take an open reflector housing, pull it apart, and install OEM projector components. if you’re skilled with a dremel tool you can probably do that in just about anything. it’s still gonna look weird in there, but you’ll have a better performing light setup. that’s beyond the level of most people who just buy a kit from ebay and plug it in.

In summation: you want aftermarket HIDs?  Get projector housings, make them if necessary. Order HID bulbs that are on par with the brightness of OEM applications.   Put it together with quality wiring and electrics. Aim them correctly.

Easy, right? 

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

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