Intermittent taillight problem without OBC message

[Jay 535i]

Some of you guys who were in Chicago know this story:

My right taillight works only occasionally over the last couple of weeks. Before that it worked fine. To be clear, I'm talking about the light that comes on in the rear when your headlights are on -- not the brake light or the turn signal, but the smaller bulb.

The bulb checks out fine, but has been replaced anyway with the geniune OE item to no avail. Interestingly, there is no warning message on the OBC informing me of a broken taillight. I am using Depo rear light clusters from ebay, which bimmerd00d and a couple of other guys suggested might be the culprit.

How do I sort this out? I really like my (admittedly cheap) Depo lights and don't want to replace them. As far as I can see there is no damage to the lights or the plastic piece that holds the bulb. I don't think anything's melted or visibly damaged?

Any ideas? And why would the OBC be silent on the issue?

[SharkmanBMW]

I would put the OEM back for awhile just to see what comes of this... if it's gone, you have your answer (depo), if not, it's wiring.

[SchnellE34]

how long have you had the depo's? i had the same problem and actually took some sand paper to the contacts, made a better connection and fixed the problem.

[swenpro]

Yes, I also had a contact issue on my taillight, even with OEM bulb installed. After using a little contact cleaner and positioning the bulb just right, I haven't had a problem since.

On another note, once in a while the OBC gives me a "Brake Light Circuit" warning and to "Check Owner's Manual". I have no idea what this is talking about, as my brake lights continue to work fine.

[TheEndIsNear]

FYI, I had the "Brake Light Circuit" warning comming on and off every now and again but when checking my lights they were fine. Then one day it popped up again and I got a ticket for no break lights. Turned out to be a worn out 'Stop Light Switch'. That's the switch attached to the break petal. Check it!!! It's a BIG ticket!!!

[Jay 535i]

how long have you had the depo's? i had the same problem and actually took some sand paper to the contacts, made a better connection and fixed the problem.

About six months. I'll try cleaning the contacts as you suggest. I still think it's strange that there's no OBC error message. I may swap the original lights back in for a few minutes to confirm the source of the problem.

Thanks for the help.

Swenpro, I had that problem in the past, too. I think many of us have had that at some point. The culprit is a bad "brake switch" under the dashboard. The part costs about $20 and takes about 30 minutes to install. No biggie, and it will solve your problem.