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99 CLK 320
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Discussion Starter · #1 ·
i've had to replace my headlight, breaklight and reverse light bulbs numerous times within a span of a few months. any ideas what's going on???
 

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1986 560sl, 2001 E320
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80 Posts
You bought a Mercedes, that's what's wrong. Don't worry, the pros far out weigh the cons and changing bulbs is simple and cheap. What model do you drive?
 

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2001 E430
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74 Posts
i don't know what the above quote is supposed to mean?....have your voltage regulator checked. might be too "hot", burning out your lights more quickly than usual. have you had your alternator changed recently? i believe the voltage regulator is integrated into the alternator, which is why i ask.
 

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99 CLK 320
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Discussion Starter · #4 ·
haven't had the voltage regulator checked nor had my alternator changed. will look into it.

btw...this is for a clk320 w208
 

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'01-E320 & 02-ST2
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31,631 Posts
When changing headlights, clean them first with alcohol, then don't touch them with your fingers or they will live a short life. Tail and brake lights, be sure the contacts on the board are nice and clean. Intermittent contact often will result in a voltage surge that cooks them off.

Check all the chassis grounds as well.

Quick check for overcharging: look at your battery water. If it's low top it up with distilled water (to the bottom of the cell overhangs) and then do be sure to check out the charging system. Overcharging will cook the battery as well.

Take care and enjoy the ride,
Greg
 

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I had a pair of halogen bulbs burn out 5 months ago, and now they burned out again. Both times, one went and the other immediately followed. I've been told that a bad ground could be the problem. Is this possible? If so, can someone explain to me how a bad ground could shorten the life of a bulb. Any other suggestions?

Driving a 2000 C280 (V-6 engine)
 

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2002 CLK 430
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191 Posts
Check Codes, where are all of the chassis ground on the W208? I've asked this question before on forums trying to (possibly) track down my 'dimming lights' issue, thinking perhaps there is more than the single main ground in the trunk/boot off the battery. Checking/cleaning others if they're large/major points of contact is my next step, but I've never heard anyone who can tall me what points these are. Thanks!
 

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'01-E320 & 02-ST2
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Check Codes, where are all of the chassis ground on the W208? I've asked this question before on forums trying to (possibly) track down my 'dimming lights' issue, thinking perhaps there is more than the single main ground in the trunk/boot off the battery. Checking/cleaning others if they're large/major points of contact is my next step, but I've never heard anyone who can tall me what points these are. Thanks!
There are two ground points under the hood, one on each side for each set of lights. Usually on the front side of the fenderwell, it's just a small stud (4mm?) with several brown wires coming to lugs that are stacked on the stud and secured with a nut. With the key in your pocket, remove the nut, use a mild metal-bristled brush on the stud, lugs and underside of the nut, and then reaffix them all, tightening firmly.

There are various other ground connections on the car as well. The engine ground strap is often overlooked, but it can certainly loosen and literally wear out as well. The connection from the battery to the chassis (the one you mention) is also of obvious importance, though problems with these latter ones manifest themselves in ways other than just dimming lights. ;)

If all of your lights are dimming, I'd spend a little time looking at the alternator and regulator. The brushes could be getting worn and hanging up a bit. If the alternator sounds okay through a steth, then were it my car I would be inclined to pull the alternator and replace the regulator (it comes with new brushes) inspecting and cleaning the commutators while I was doing so.

Hope that helps, good luck to you.
 

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2002 CLK 430
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191 Posts
Some more good intimation - thank you again, Check Codes (you're on a roll today with my questions!)! I have replaced the alternator (~1 year ago), though having an aftermarket stereo system makes every mechanic's finger point to that when there's an issue. However, the dimming persisted after the new alternator and still manifests itself when the stereo is off and/or disconnected. Hence my curiosity about additional grounding points. I'll have to give these a look.
 

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101 Posts
I had a pair of halogen bulbs burn out 5 months ago, and now they burned out again. Both times, one went and the other immediately followed. I've been told that a bad ground could be the problem. Is this possible? If so, can someone explain to me how a bad ground could shorten the life of a bulb. Any other suggestions?

Driving a 2000 C280 (V-6 engine)
Hallo!

I am not sure about ground issue. Theoretically bad ground should reduce voltage across bulb (Ohm law), so then lifespan of bulb should increase.

However halogen bulb are very susceptible to "skin oil" on the glass. It makes a "hot spot" at that area of glass, and it can make glass change its crystal state because of overheating, letting halogen gas permeate across and then when halogen gas is gone, the filament evaporates and condenses on glass side since no halogen is there to "recycle" (this is my understanding). I should add, regular bulb should not care about this very much.

FWIW I put regular bulb in my citylight that I had lying around from some old car, and it worked for 1 day! But then I replaced it with another bulb just as old, and it works fine already 1 month...
 
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