W124 Warning Lamp on Dashboard

[phoenix_nights]

The W124 estate i bought had the warning lamp indicator on which basically says if you have a blown bulb.(did not flash on indicating which meant it was not one of the indicators) I found that my licence plate had one blown bulb but and replaced it but the warning lamp is still on.

From reading posts here i figure my next option is to go thru all the lights and clean the connections. Is that right. Is there something special i should be using to clean the connections. Can i used copper wire or something on each connection to test or something.

I am determined to get this fixed.

Cheers....

 

[Howard]

The bulb warning light won't flash on indicating, but you will hear the 'clicker' going at double speed if you have an indicator out....

W124's are sometimes sensitive to cheap bulbs, all the lights can work but the light will still be on if someone has used bargain basement bulbs...

Even more bizarrely the light can sometimes come on when a bulb is about to go soon , thdy are that sensitive....

Check all the connections, use a bit of emery cloth to clean them .... then check all the lights again, including foglight bulbs..... which sometimes get forgotten ....

good luck

EDIT :- have a search using 'W124 bulb warning' as the criteria, that should give some more info ...

 

[phoenix_nights]

Thanks Howard. Forgot about the fog lights and did as you suggested and did more searching on the forum and wil check parking lights and rear cluster . I figure there is no fuse for this light in case i can't get to the bottom of it

The bulb warning light won't flash on indicating, but you will hear the 'clicker' going at double speed if you have an indicator out....

W124's are sometimes sensitive to cheap bulbs, all the lights can work but the light will still be on if someone has used bargain basement bulbs...

Even more bizarrely the light can sometimes come on when a bulb is about to go soon , thdy are that sensitive....

Check all the connections, use a bit of emery cloth to clean them .... then check all the lights again, including foglight bulbs..... which sometimes get forgotten ....

good luck

EDIT :- have a search using 'W124 bulb warning' as the criteria, that should give some more info ...

 

[aka$h]

Check the bulbs are the right wattage, if there not it will cause the same thing to happen.

 

[Shude]

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

 

[bolide]

W124 bulb warning

The usual suspects when this happens are front sidelights and wrong-wattage rear sidelights. People tend to fit 10W rears when they should be 6W (hope I've got those numbers right!). Those bulbs darken with age so I replace them as a matter of course. Wrong wattage brings up the bulb failure light. The other suspects are the number plate lights

Things get tricky when the wiring to the tailgate fractures and you get intermittent connections or none at all. This is a known problem with older W124s and the doors are affected too. The cables fracture where they flex as they pass through the rubber guide tube to the door/tailgate. The only cure is to cut the broken bit out & replace it

The bulb warning works on the brilliantly elegant principle of the Wheatstone Bridge. The wiring for the car is divided into two sides and each side (sidelight front left and sidelight front right, etc) is compared with the other. If both bulbs are OK then both sides draw the same current and the voltages acros the two are the same. So if you connect one side to the other no current will flow between the two as the voltages are the same. If one bulb has gone there's a voltage difference between the two, a current flows and the bulb failure warning unit is triggered

You'll notice I've omitted to say what happens with the rear fog light as there's only one...

Nick Froome
www.w124.co.uk

 

[phoenix_nights]

Thanks Shude and Bolide. Have printed out your post Shude and will try it tonight. Bolide thanks for the info., love knowing how these things work.

 

[Howard]

Thats ok .....don't thank me , i do it for a living

 

[turbominor]

mine was on for about 2 months but all the lamps were working, some helpfull motorist pointed out that one of my brake lamps was flickering occasionaly...

took bulb out to find the fillament had burnt out and was re attaching its self... and i presume was making the lamp flicker..

 

[basmar]

correct bulb

I had the same issue on my previous car (W124) all the lights were working ok.. spent many hours trying to track down the problem... eventually my local MB specialist found the issued to be a bulb with the incorrect wattage!! after they replaced the offending bub I had no further problems

 

[phoenix_nights]

Howard if you notice on the thread i thanked you for your contribution already Ok another special thank you to the man in the white mercedes. (..why is everyone running away )

Thats ok .....don't thank me , i do it for a living