I'm looking for assistance with a headlight issue and I'm hoping the collective knowledge base at sUSA would come up with a resolution.

I had two headlights of different ages blow about a month ago at the same time. It happened the day before I was going to the dealer so I picked up some more expensive brighter lamps and had the dealer put them in. I asked them to diagnose what would cause two lamps of dissimilar age to die at the same time. They gave me some bull about it being a coincidence, that both blowing at the same time is rare but no unheard of.

I didn't fully buy it, but figured they're the experts. One month later they both went out again at the same time. I've got an 08 and haven't had any issues until my right lamp went out last winter. At the time I didn't think anything of a 3 year old bulb going. Still don't. However, now that I've had two pairs go in a month, obviously something wrong.

I found your old post about the A 451 540 23 06 resistance kit that limits voltage to the lamps but that sounds like a "patch" as opposed to a repair. Do anyone know of a better fix or is the resistance kit the only option?



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Yes, there's a remedy. Use the stock bulbs, or standard brightness bulbs. The brighter bulbs can't handle the vibration and will blow out quickly. Buying brighter bulbs is a waste of your money.
3 years on a headlight bulb is considered normal.


Thanks for the input. I don’t' think that's the issue. Since the last post I didn't have time to get to the dealer. During that time they came back on and have stayed on. So I must have a loose connection somewhere.

Now I've got to figure out what is the common denominator between the two lights.

All the best,


Hi Mark:

Which light came on and stayed on?  Are they both blowing out simultaneously or did one of them blow out?  While the lights were out, are you saying both of them randomly came back to life?

Both went out at the same time twice. The first time was an orignial stock headlamp and one that had already been replaced. Since I was due for service anyway, I had the dealer replace both with brighter lamps I purchased at Walmart. One week later both of the new lamps went out.

My assumtion was I had an electrical issue that was blowing the bulbs. However, I never pulled the lamps to test for continuity. For the next couple of weeks I didn't have time to go to the dealer. All of a sudden I turned the lights on and they came on. So now I now the issue isn't surges to the lamps. I'm assuming its a loose connection at a common point somewhere ahead of the lamps. Since each lamp is separately fused it has to be before the fuses.

If I can get my hand on a wiring diagram I should be able to find the issue. Either that or maybe someone who has experienced this will be able to tell me whats up. 

Well, what happened when you tested the lamps for continuity?  Did you test the headlight switch?

Since the lights both work, continuity is not their issue. As for continuity elsewhere in the lighitng circuit I'm not sure how to check it. Even if I did, I have to wait until the circuit fails. What I need is  circuit diagram.

That way when it fails, and now I'm assuming it's a loose connection that will fail. I have a shot at solving the issue if I have a wiring diagram. 

Hi Mark,

There could be some credence to the theory of a surge causing the lights to fail. Authorized smart centers are in the best position to address these types of concerns since they have the proper diagnostic tools and equipment necessary to provide you with a solution.  Or even call smart directly at 1-800-367-6372, they may be able to coordinate with the smart center to help resolve this for you!



Originally I thought it was a surge but the fuses never blew and the lights came back on. If it was a surge as I originally thought I would think that either the fuse would blow or the light filament would blow out. However, when the both lamps came back on the only thing that was blown was my surge theory.

On another smart site SCOA I chatted with someone who who's very knowledgeable with the car. He thought the issue could be a high voltage creating the problem because older smarts were known to sometimes have that issue. Even though my car was good for three years I thought he was probably correct. Then the lights came back on. If they were blown out due to high voltage, again they would not come back on.

So I'm leaning towards a loose connection. Of course I still could be wrong. Certainly my dealer was incorrect, the first time both lights went out at the same time they simply chalked it up to a grand coincidence. NOT.

It seems like the service I'm getting from the dealer I bought at is slowly getting worse. Luckily, we have another dealer in the area. I'm going to try them if I can't dig up a schematic myself.

Thanks for the input. I do like the idea of calling smart directly. If nothing else they may have heard of this issue and can advise me of a fix. Even if I'm not capable or don't have the right tools, I can let the dealer know what to look for.

All the best,



Mark, if your headlights are still working on the same bulbs but they are flickering on or off then you need to have a technician check the following

-headlight switch inside the car for proper function

-secure electrical connection at the headlights

-headlight relay

-wiring for continuity

It will require a labor commitment however so it likely won't be free.  I hope this helps you.



I suffer with the same problem on my roadster.

I am using curently philips vision lamps H7 55 watt. I changed them recently left and right in between 2 weeks from eachother. They ran aprox 5 months.

Now I replaced  the original crap connectors by H7 porcelan connectors,as I hope they fitt better and wil not give any bad contacts due to vibration.

I keep posted as soon as I am having results.


grts little 911-er

A few reasons for headlight bulb failure....

xtra bright have a much shorter overall lifespan than the standard oem bulbs.  The filament is put under more stress for higher output.

Changing bulbs with dirty hands leaves your natural oils on the bulb glass which shortens bulb life. Use gloves.

Front end shock and vibration of the smart car also adds stress to the bulb filament.

The smart car electrical system outputs strong voltage (it's slightly higher than average, but could be considered high output for a 1.0L engine) primarily because of the safety systems and the transmission shifting.

At the end of the day, using the extra bright/ultra bright bulbs is not a big deal as long as you're willing to accept the tradeoff of more frequent headlight burnouts. 

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