External bulb failure on dash ?

paulfoel

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Mine lit up the other day (and found out what it meant by looking in the manual)...

Anyway, turns out one of my brake light bulbs had popped. Replaced this and it worked.

Trouble is dashboard light is still on.

Can't see any other bulbs out. Any ideas ?
 

jimmy

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The bulb failure warning should reset itself every time you turn the ignition off. Next time a bulb does not work it will light up again. You must have another dodgy bulb, checked the reverse lights?
 

andy_k

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you need to isolate which bulb is setting the warning off.....

1, does it come on when you turn on the lights and go off again when you switch them off? - if so a check of all the bulbs will usually show one that is either not working or dimmer than the others - nearside tail light seems to be a favourite for causing this problem, although the bulb is lit it's not got a clean connection - remedy, clean the contacts and replace both rear bulbs.

2, does it come on when you put the car in revers then go out again when you put it in drive? - if so one or both the reversing lamps are out.

3, and most likely, does it come on when you apply the brakes and then not go out again until you restart the car? - if so one of the brake lights isn't working. Replace them both and don't buy the bulbs from Halfords as a few on here will vouch for, they seem to make their bulb sleeves ever so slightly smaller than everyone else so they never make a proper contact in the bulb holders

The bulb warning circuit on Mercs is incredible sensitive so the slightest bit of dirt, corrosion etc on the terminals can cause problems.

HTH

Andy
 

sym

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Originally posted by andy_k
you need to isolate which bulb is setting the warning off.....

1, does it come on when you turn on the lights and go off again when you switch them off? - if so a check of all the bulbs will usually show one that is either not working or dimmer than the others - nearside tail light seems to be a favourite for causing this problem, although the bulb is lit it's not got a clean connection - remedy, clean the contacts and replace both rear bulbs.

2, does it come on when you put the car in revers then go out again when you put it in drive? - if so one or both the reversing lamps are out.

3, and most likely, does it come on when you apply the brakes and then not go out again until you restart the car? - if so one of the brake lights isn't working. Replace them both and don't buy the bulbs from Halfords as a few on here will vouch for, they seem to make their bulb sleeves ever so slightly smaller than everyone else so they never make a proper contact in the bulb holders

The bulb warning circuit on Mercs is incredible sensitive so the slightest bit of dirt, corrosion etc on the terminals can cause problems.

HTH

Andy

I wish mine was that helpful !

Unfortunately it doesn't seem to go on and off when the offending bulb circuit is activated - it is off when the car starts, and then as soon as the blown bulb tries to activate, it is on, and stays on. So you have to use a process of elimination to work out which bulb has failed by turning the ignition off and then on again to reset the bulb-out light.

Or alternatively, run all the lights at once and inspect the exterior of the car to see which one is out !

S.
 

BaldGuy

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We had a thread not long ago that mentioned that bad fitting bulbs will keep the dash light on. It turned out that the Halfords etc equivalents were not big enough for the socket thus giving false readings. Also giving you brake lights that flash like a Crimbo tree....

Just a thought.....
 

bazza

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I'm glad all I need is a large window!

The problem with gadgets is that they will go wrong, and they WILL cost a lot of money to fix.

My dad had a 1983 Datsun Bluebird and it had a bulb failure system on it. I thought it was great at the time,but when he replaced a faulty bulb it went out, no resetting or wrong type of bulbs, etc.
Progress eh?

My father in law has a 2001 C200K Coupe thing and it is never out of the dealers for niggly faults. His SLK has been OK, but he hated the C180 sport he had. Not enough oomph and the autobox never did what it was meant to.
He still yearns after his old 190E though, but he can't have it, it's mine!!


Bazza
 

Shude

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Originally posted by Wheelie
We had a thread not long ago that mentioned that bad fitting bulbs will keep the dash light on. It turned out that the Halfords etc equivalents were not big enough for the socket thus giving false readings. Also giving you brake lights that flash like a Crimbo tree....
In my case they now don't work and you don't get a dash warning light either, I have to remember to tap the offside taillight before I get into the car to make sure I have a working brake and reverse light on that side! New bulb time I think...
 

Steve_Perry

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Originally posted by Shude
In my case they now don't work and you don't get a dash warning light either, I have to remember to tap the offside taillight before I get into the car to make sure I have a working brake and reverse light on that side! New bulb time I think...

Nick,

How come your failed lights indicator doesn't work? I thought those things were sensitive to a gnat's fart from 50 yards...

S.
 

Shude

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Originally posted by Steve_Perry
How come your failed lights indicator doesn't work? I thought those things were sensitive to a gnat's fart from 50 yards...
no idea, it's possible that the bulb rattling in the slightly larger holder takes the current elsewhere or something. It's going to be investigated soon anyway (replacing the bulbs).
 

Steve_Perry

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Originally posted by Shude
no idea, it's possible that the bulb rattling in the slightly larger holder takes the current elsewhere or something. It's going to be investigated soon anyway (replacing the bulbs).

Do I smell a mod coming on? :D Or are you just replacing bulbs with non 'Hellfrauds' ones?

*EDIT* I guess this answers my question :D

S.
 
Last edited:

GregE240

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I had a similar problem, as discussed on my thread titled "Bulb Failure...but no bulb failed?"

In conclusion, the failure circuit is very sensitive to current it would appear. All I can suggest you do is the following:

1) If you have replaced your bulb with a non MB bulb, change it to one from a dealer, particularly if its the stop/tail light. The little spigots on the bayonet are not quite at 180 degrees to each other (as per conventoinal stop/tail bulbs). These WILL work, but won't sit in the holder correctly.

2) When I replaced my stop/tail bulbs and my reverse bulbs I found that the "springs" that connect the bulb holder to the printed circuit had gone a bit soft, not making a good connection. I found that if I performed "The Shude Manuevre" on the light cluster (i.e. give it a good thump) it worked. Remove the holders and get a small screwdriver under the springs and pull them up a bit. They'll make a better connection.

3) If its headlight bulb related, it seems one of my connectors in the headlight unit (W210) had a bit of a dry joint going on. I recrimped mine with thin nose pliers and that seems to have sorted it.

I hope this helps. Trial and error is going to be the only way you will find the offending bulb/holder.

Greg
 

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