Faulty Bulb Out Warning Light

[Karl W]

Hiya the bulb failure warning light is coming on now and again without reason. All the external lights are OK. How does the system work, and is there a control unit somwhere thats playing up and due for changing ? The wiring all looks OK at the back of the lights front and rear.

Thanks for reading

 

[BlackC55]

Number plate bulbs ok?

 

[Karl W]

Yeah the number plates are fine, thats what I first thought may have gone. The cars and old W124 estate

 

[JOB-BLACK-RAT]

I had the very same problem last week.

Was actually the result of a loose conection on the brake light bulb so it was correctly telling me the bub was out. Changed the bulb and made sure the fit was snug and no problems agains.

 

[Karl W]

I had the very same problem last week.

Was actually the result of a loose conection on the brake light bulb so it was correctly telling me the bub was out. Changed the bulb and made sure the fit was snug and no problems agains.

I'll have a look, I've got a sneeky suspision there's some water getting in to the left brake light, after poking around this afternoon. I've found out to make sure the bulbs in rear especially are all making a firm contact and that all the other the bulbs are of correct wattage. So just to be on the safe side I'm giving them all a check over.

 

[Karl W]

Replaced the the rear light bulb holder and no problems so far, even tested it with some blown bulbs and its wroking fine now

 

[GP801]

The warning is very sensitive. It can detect a bulb on the verge of blowing but still working. I think measures change in resistance. Common culprits on 124 are tail light and number plate lights. If it comes on when braking it will be the brake lights. Best to change in matched pairs if one goes.

 

[mapleleaf]

i have the same problem with my w210 estate - changed rear stop lights but problem recurred - so looks like its the holder (s) that need changing.

 

[crankiejohn]

poor wiring connections,poor earth on the bulb or holder contacts,bad earth on body earth points,a bulb starting to burn out or somtimes just different makes of bulb can activate the relay.

 

[jonnyboy]

Any time i have this problem i replace the brake/tail/number plate/sidelight bulbs with matched new pairs in sequence. 5/10 times its the tail/number plate ones. I find better results with branded over "hellfrauds" ones.

 

[bh13coupe]

Yep, my rear number plate bulb sweated me out for a week found it in the end, the give away was the dash light flickered off when the boot was slammed by the mrs whilst i was sat in the car.

 

[Olivier]

Same here, I was looking everywhere, pressing the brakes and all, couldn't find the bugger, it was one of the plate bulb, it was hard to see as well as there are 2, then seeing some light there I never thought it was the bother. Tricky bugger.

 

[Monika]

Flickering Lights

Number plate bulbs ok?

I seem to be having a similar faulty warning issue of bulb failure warning light coming on now and again without reason. All the external lights are OK. I checked the number plate lights and look O.K. but every now & again I get the fault message. Do I have to change the lamps????? At the same time I have also noticed that the lights (including the interior cabin light, cluster lights & all external lamps) flicker very slightly when the enigine is running or ideling. I WONDER IF THE ISSUE IS RELATED???
LASTLY, When both the front seat massage (pulse switch) are turned on than the seat massage operates for a very short while. When switch is reactivated it would BLINK for a few seconds and go off. Any suggestions????

Thanks for reading & responses welcome.

 

[James1976]

I found the problem in my car was bodged wiring to overcome a faulty relay. Turned the lights on and even though all bulbs came on due to the bodge, the warning light was still correctly on. Apparently the solder in the relays can crack with age producing these problems. I replaced the relay and removed the bodge and then the werning light worked (and went out). Apparently it's possible to re-solder the contacts if you open the relay carefully. Just a thought! J

 

[derin100]

Bugger! Wish I read this thread first! Just had this issue on the 300CE I'm currently renovating.
All lights working but as soon as you switched on sidelights the warning illuminated. Therefore, cleaned all the contacts to the front and rear lights, changed both front sidelight bulbs and rear bulbs in pairs for new ones, changed every single fuse. Still no joy!

I forgot to change the rear licence plate bulb even though I had looked to see that both were working....which they were. Turned out (after reading this thread) that's what it was! One of the licence plate bulbs was the culprit.

 

[Lxb3]

One other thing it could possibly be (I've got to investigate this on the T124 E220 myself) is towbar electrics... mine are wired in on the driver's side, so I would guess that this must have some tiny effect on the resistance on that side of the car...