W124 bulb not working warning lamp

[JumboBeef]

My W124 has the bulb-not-working warning lamp on the dashboard on all the time (when side and/or headlights are switched on), even though all the bulbs are working OK.

Any ideas why this is, or can I disable this warning lamp somehow?

Thanks!

 

[BlackC55]

You either have a wrong wattage bulb fitted or a loose connection or there is a fault with the switch.

 

[JumboBeef]

OK thanks. Can I disable this warning function in anyway please?

 

[JumboBeef]

...to add, I want to add a high level LED brake light as well. Would this upset this warning system too?

 

[Dieselman]

You can add another lamp as the original bulbs will create the return to Gnd the warning system uses.

Check all bulbs and holders carefully, including the number plate lamps.

 

[Frank O' Phile]

Check and clean all the bulb holders in the rear clusters. They are favourites for furring up and causing poor contact. Remember number plates lights too.

As above, the wrong wattage bulb will do it too.

Not sure about the hi level lamp.

 

[Smiley]

most common fault is 5 watt bulbs fitted in the rear tail lights - they should be 10w. This will cause the bulb failure light to come on.

 

[JumboBeef]

Thanks!

...but is there anyweay to disable this function totally? I hate bulb-out warning lights: I used to have Jags and they had such a function which was always warning me of a bulb out, when there wasn't (such as now).

 

[BlackC55]

They are very useful and and a added safety feature. I would rather have it than not.

 

[JumboBeef]

Fair enough! However, I would like to disable it, anyone know how?

 

[SilverSaloon]

take the cluster out and pull the bulb out to disable.

i prefer to have it and fix the issue why it has come on. you have incorrect bulbs in your car or one thats out - fix it instead of just pulling the bulb. you wouldnt pull the low oil light if it was on would you? you would top up the oil - no differerence as far as i can see

fitting an LED centre brake light shouldnt affect it if its LED. thats what i was told anyway when i was considering it.

 

[JumboBeef]

take the cluster out and pull the bulb out to disable.

Thanks....but how do I get to the cluster?

i prefer to have it and fix the issue why it has come on. you have incorrect bulbs in your car or one thats out - fix it instead of just pulling the bulb. you wouldnt pull the low oil light if it was on would you? you would top up the oil - no differerence as far as i can see

I would agree......if the damn thing worked OK! All the bulbs work, there isn't an issue yet it is telling me there is a problem. I had the same with the Jags I had, all bulbs working yet it would keeping telling me there was a problem! I can also see there are other threads in this section from other people with the same issue on other MBs. The answer seems to be to waste time cleaning or replacing perfectly good bulbs, just to get this warning lamp to go off.

Would you trust your oil warning lamp if it kept just lighting up for no reason?

fitting an LED centre brake light shouldnt affect it if its LED. thats what i was told anyway when i was considering it.

Thanks!

 

[andy_k]

Thanks....but how do I get to the cluster?



I would agree......if the damn thing worked OK! All the bulbs work, there isn't an issue yet it is telling me there is a problem. I had the same with the Jags I had, all bulbs working yet it would keeping telling me there was a problem! I can also see there are other threads in this section from other people with the same issue on other MBs. The answer seems to be to waste time cleaning or replacing perfectly good bulbs, just to get this warning lamp to go off.

Would you trust your oil warning lamp if it kept just lighting up for no reason?



Thanks!

the safest way to get the cluster out (ie without damaging it) is to drop the trim below the steering column, reach up and just push it out - they are a friction fit.

If it's a mechanical speedo you'll ned to disconnect the cable to get it oput far enough to reach the bulbs you want to get at.

The bulb warning light doesn't just light up for no reason - trust me, I'm one of those who had a similar problem. It turned out one of my rear clusters was corroded and a front sidelight wasn't seated properly.

I'd rather have the function that disable it.

 

[JumboBeef]

OK, thanks. I will take another look at the bulbs before disabling the unit.

As this bulb-out warning comes on when I switch the side lights on, I assume it will be either one of the two front side lights, the two tail lights or the two number plate lamps which is causing the problem...........?

 

[andy_k]

yep - the number plate lights are a favourite - the connections corrode and throw up warnings.

I'd try and troubleshoot it - better to have a warning on the dash than a fixed penalty for having a bulb out

 

[JumboBeef]

I've just noticed: the cig lighter goes off when I switch the lights on..........

I plugged my TomTom in, and all works OK. I switched the lights on to try and find the bulb which is throwing the bulb-not-working fault up, and I noticed the TomTom lost power.

Any ideas why it is doing this? Could it be connected the the bulb-not-working fault I have?

Thanks!

 

[andy_k]

I would have thought they were on seperate circuits - the cigarette lighter should be on with either the ignition or the front doors open (you didn't close the doors did you?) whereas the lights should be a constant live.

Still check the rear number plate lights and the wiring that feeds them.

 

[JumboBeef]

I had a look this afternoon, and........

most common fault is 5 watt bulbs fitted in the rear tail lights - they should be 10w. This will cause the bulb failure light to come on.

...........one tail light did have a 5w in it. I don't have any 10w's here so hopefully once I get some tomorrow, that will be that problem sorted.

I fitted the high level LED brake light, without problem (and it makes the rear look more modern too).

The lighter is now working as it should: I really don't understand that problem

Thanks for all the advice.

 

[JumboBeef]

Right, 5w lamp replaced with 10w and.............it works, and no bulb-out warning.

I think I was judging this system on the Jags I used to have (both were XJ40) and that system is total pants!

Thanks for all the help!