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Blown bulb warning lamp on W124

MDMB69

New Member
Joined
Dec 3, 2004
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19
Location
Derby UK
Car
E280TE
1996 W124 E280. I have the little yellow warning lamp come on, on the dash when I switch my lights on. It's supposed to indicate a blown bulb, however I've checked them all and they all work. So why am I getting this warning lamp illuminated? Any ideas?
 
I think you probably have missed one. The warning lamp is pretty accurate as it will pick up any wattage that is less than what it should be. It could be the reverse lights or even the fog ones. Have you also checked the small side indicators and interior room lamps?
 
Check the rear number plate lamps too...;)

Sometimes the blown bulb warning indicator activates when it detects/senses that a bulb is about to fail as well. Avoid cheap Halford bulbs and instead get the better quality bulbs from the Stealerships which are reasonably priced.
 
From an earlier post:
Shude said:
I don't know if this sounds obvious but you should be able to establish which bulb or set of bulbs the failed/failing one is in. I'm sure someone else has posted something similar to this.

With the engine running (beware the reverse gear check, best tested with the engine stopped although the dash light will be permanently lit).

Turn dial once and sidelights go on; failed? It's one of 6 (possibly 8) bulbs, sidelights front (2), rear lamps (2 or 4) or licence plate lamps (2)
Turn dial to next level, headlamps; failed? It's a headlamp bulb (2)
push indicator lever forwards; failed? Beam (2)
Pull dial out once; failed? front fogs (2)
once more; failed? rear fog lamp (usually just the one although there is probably a second bulb inactive in the opposite housing)
Indicate either direction; failed (if not obvious at 2x the speed ;) ) then it's probably a wing repeater (2 total)
Touch brake pedal; failed? brake lamps, this usually stays on even if you take your foot off the brake (2 lamps, sometimes three but the later LED cluster may not register)
select reverse gear; failed? reverse bulb (2).

I think that's it although I'm prepared to be told where I'm wrong :)
I have yet to have any feedback on that process but I think it's basically correct.
 
Mine comes on occasionally when its damp. Suspect there must be a dodgy connection somewhere, but as it's intermittent its never on when I've got time to investigate.
 
Someone once told me that Mb bulbs are a tiny bit bigger in the base than ordinary ones. If this is true then vibration would cause a slight fluctuation in current therefore making the warning light come on. Dont take this as gospel, just what I heard and it could be a load of hogwash.
 
I think that the MB bulbs have an extra prongy bit (excuse the non technical jargon) that is missing on non MB bulbs that results in the warning light coming on.

Another place to check is the number plate lights, some models have two bulbs in there, so at first glance can look as if they are working.
 
MB use bosch bulbs pretty much exclusively, there is no "MB Bulb" I'm afraid.
 
Shude said:
MB use bosch bulbs pretty much exclusively, there is no "MB Bulb" I'm afraid.

By MB Bulb I am referring to a bulb purchased from a Mercedes Dealership.
 
Off Topic: one thing that annoys me is seeing brake lights/rear lights on cars that have bulbs of the wrong spec i.e. brightness - normal one side and dim or too bright on the other side...:crazy:

I was following one "barry" done up car a little while ago at night time and he had "fog light" rear bulbs fitted in place of the rear lights as well as 2* fog lamps on the rear all on at the same time and was really hurting my eyes. It was not safe to overtake so I turned the hi beam on the bi xenon headlamps to give him a taste of his own medicine...:devil:
 
Hi there,

On the w124's , the lighting fault circuit is notoriously sensitive ..... it can even trigger a warning if a bulb is about to go soon .... as the filament degrades , this can cause it to display the warning ...

Inferior quality bulbs can also make it display a warning (Hellfrauds own brand for eg.) best to use good quality ones ....

Have you checked every single bulb (number plate lights x 2 , foglights etc) and check for looseness as i had a front foglight on my w124 that seemed OK but yet triggered the warning every time i put it on ....

If someone has put LED's in to replace the normal bulbs, this can trigger it as there is not enough load on the circuit ( LED's draw much less power ) and this will trigger it too .....

good luck

H
 
check the wattage of your rear tail light bulbs!! they are available in 5&10 watt check you have the correct ones fitted;)
 
It was the rear number plate light. Can't believe I never spotted it. 2 minute job to fix.
 
Excellent, nice to read that it's sorted! :)
 

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