Bad Lightbulb On Headlight

[Lito 2]

One of my lights burned and when I replaced it, I found the base was all "burned up". The filament was bad, so that was the real reason of it not working, but the "burned" bit worried me. Is it normal for it to receive so much heat that the base kind of melts? The female lead appears to be OK.

Edited March 25, 2013 by Lito

[GoFaster 9]

Not normal, but it's possible that the filament had a partial short-circuit (internally) and ran excessively hot for the last few seconds of its life. I've seen it happen on other vehicles.Looks like a normal H7 bulb.

[Lito 2]

Yes, it is a regular H7. It is only that I am inexperienced and had never seen anything like it before. Thank you!

[marchanna 115]

Heat can be generated when you have a poor contact, that can be caused by dirt or a little corrosion. I like to treat any electrical contacts with some dielectric grease - this resolves a lot of "gremlins".

[stickman007 309]

A good read on headlight wiring: http://www.danielsternlighting.com/tech/relays/relays.html

Just burnt out another bulb…my coupe is going through bulbs much faster than my cabrio - one every 4-5month-ish. I'm temped to relay my headlights.

Edited November 12, 2013 by stickman007

[marchanna 115]

I would take a look at the connectors. If they're arcing a little it will shorten the bulb life. If there's any corrosion or residue, file or sand it then treat with dielectric grease.

[Lito 2]

Since bulb was replaced, I have had no trouble, so I am assuming it was just the bulb.

[marchanna 115]

Yeah, that could very well be the case. How did the connector on the car look? Was there any heat damage to it?

[jzchen 0]

Yeah, that could very well be the case. How did the connector on the car look? Was there any heat damage to it?

OP said the female lead looks okay. I took this to mean the receptacle wasn't damaged. I saw on another forum about bulbs prematurely burning out. There is some sort of resistor part that Mercedes adds to newer models and can be retrofitted to older models. I wish I kept a tab on the thread/part number...

[FlossyTheSmart 81]

That part number would be A-451-540-23-06

Pulled that from a SCoA thread HERE

[jwight 117]

Just a reminder that the resistance kit is not needed on 451s manufactured since December 2010, per this smartusainsider.com FAQ:

6) Why are my headlights burning out quickly?Headlamp bulbs can be sensitive to higher system voltages on cars. There is a resistance kit (A 451 540 23 06) that can be installed to reduce the voltage on the headlamps and prolong their life. Headlamps with integrated resistors have been installed in production since December 2010.

http://www.smartusainsider.com/faq#faq06