One Brake Failing Erratically - Resets

[lhfixer]

Hello! I have a 2001 MB E240 Elegance Wagon S210

Problem: My right side brake light fails but works for a period of time when the bulb carrier is reseated.

Is there a fickle thing with these I'm not seeing? Is there some kind of power short protection - that is not a fusible link - that is failing and can be reset by reseating the bulb carrier? What would be the point of fuses if you can cut power to a single bulb?

Background: I have this odd problem. I had a brake light out but only on the right side - So I changed it. It failed again - so I changed it. It failed a third time - so I swapped sides completely with the bulbs and bulbs carriers, They both worked! Then the right one failed in a day. I simply reseated the bulb carrier and it worked for three days. Then it failed again. Each time I get a bulb out error on the cluster.

My logical path:
- Its not the bulb carrier because I swapped them

- Its not corrosion because I pulled all of the bulb carriers and scraped the contacts clean.

- Its not blown fuses, though I checked, because I'd be replacing them over and over and not reseating this one bulb

- I don't think its a relay? Can they fail like this?

- It doesn't seem to be bare wiring because sometimes it fails in the driveway and sometimes it goes for days and days without failing

- Its not the bulbs or a loose filament. I replaced the bulbs and swapped sides.


Thank you in advance for your time!

 

[mattkh]

Have you been using the same brand of bulb. If so, which one ?

 

[mattkh]

- I don't think its a relay?
Thank you in advance for your time!

Which relay are you thinking of..?
Where is it located..?

 

[lhfixer]

Have you been using the same brand of bulb. If so, which one ?

I think they're Bosch but again if I swap them left and right its always the right going off and right back on when reseated.

 

[lhfixer]

Which relay are you thinking of..?
Where is it located..?

I honestly do not know. In the weeks that I have been looking for the solution I found a forum post here where a guy had a similar problem but it was a loose wire and someone mentioned a relay. I'm out of ideas is all.

I'd put it down to wire wear or an otherwise exposed wire if I couldn't simply pull the bulb carrier and put it right back in and have it work - all while sitting still in the driveway. I can see no patter to the failure - sometimes its minutes, sometimes days - and is always immediately fixed for a time by just that quarter turn out and back in. Reseating it with the ignition on or the ignition off does not create an error condition just some unknown thing.

 

[mattkh]

Next time it happens, please put up a picture of the bulb seat.

 

[star]

Check the contacts on the lamp, the plastic behind the bulb holder contact melts so giving a poor connection.

 

[mioba]

Sounds like the carrier to me on the brake bulb (I assume no other bulbs in that cluster have any issues - reverse light, indicator, night lights), perhaps a crack in the tracks, loose seating, which only becomes evident after driving and jolting the carrier/connections to the bulb.

I say this because you mention that after you swapped them over, the right one was then ok for a few days.

A poor connection to the bulb, effectivly making it spark, flicker will kill it in no time.

If possible get the carrier out and check the continity at the brake bulb socket, giving the unit a shake at the time, this will id a break a in the circuit. Otherwise with the unit out, have someone in the car depressing brake and at the same time give the brake bulb a wiggle, if it flickers, then its the bulb holder contacts.

btw I fing merc bulbs last a very long time.

Good luck