[Brice.omalley]

Hey guys so I haven’t been able to find a thread that tackles this issue and I’m not sure how common it is, but my left rear brake light and turn signal malfunction came on about 3 weeks ago. I did some research and found that it could just be the bulbs so I replaced both of them, and cleared the codes. I turned the car back on and it Appeared to be fine when I tested the turn signal, but when I hit the brake it gave the same malfunction. This was the code that popped up 804872 output BL_L defective. I took apart the whole housing again, and tried once more just to see if I put a bulb in wrong ect. Once I turned the car back on, both codes appeared. Out of sheer luck I tapped the physical taillight and both codes went away, tapped it a few more times and they came back on. So now I’m down to thinking it’s a bad wiring harness or the wires that go into the housing could of lost their saudering and are not truly in there. Has anyone experienced this problem, or tried to resauder or just replace the whole harness? Thanks for the help

[Billfitz]

Check the connector between the car and the lamp. Chances are the negative terminal is toast. It's very common, so much so that most dealers stock replacement connectors. Many threads about it.

[Brice.omalley]

Originally Posted by Billfitz

Check the connector between the car and the lamp. Chances are the negative terminal is toast. It's very common, so much so that most dealers stock replacement connectors. Many threads about it.

Sounds good. I will check that out today. Thanks for the help! I’ll have to see what my local dealer would cost to buy a new connector.

[DJSF3014]

I'm kinda having a similar issue I just installed new depo taillights and I have the same malfunction code only thing is it goes away sometimes after a few minutes sometimes like literally right away. All lights for that side work wondering what it could be? I've seen a video where the little metal tabs might be out far enough was looking for some opinions thanks.

[Billfitz]

That's usually the sign of an intermittent connection, which is one symptom of a bad connector.

[DJSF3014]

Originally Posted by Billfitz

That's usually the sign of an intermittent connection, which is one symptom of a bad connector.

Ahh so it might have been a bad connector from the depo ones or mine cause oem lights that came with the car had no problem.

[Billfitz]

The problem is the OEM connector. I assume the DEPO tail light uses the OEM connector that's on the wires coming out of the trunk to the lamp. Check this out:
https://f30.bimmerpost.com/forums/sh...ight+connector

[Sushi Eater]

In my case, a burned positive terminal of the light bulb caused "Rear brake lump malfunction" that sometime happens and sometimes it doesn't. I learned that the connector to the brake light assembly is a common source of this error, but mine looked fine; all pins look good.

Then I noticed the metal terminal to catch the positive terminal of the bulb may be scorched like in the attached picture, so I bent it in the hope that a surrounding good spot makes a good contact. This strategy worked and the error hasn't come back for a few weeks now.

I plan to cover the burned area with solder when I find the solder gun I misplaced.

[gatorbill75]

I had the same intermittent problem with my car frequently getting "right brake light malfunction" failure indications even though the brake lights were working correctly and on inspection the light bulb and all connections were perfect.

Looking closely at how the light bulb went into the socket I realized that the bulb rested in the socket too loose. As a result the connection between the bulb and the socket was likely to be intermittent, specially due to vibration in a moving car. My fix was to insert a thin wire into the socket at the indicated position in the image below. When the bulb is then inserted into the socket it fits much more snuggly, ensuring a good connection.

I used a small gauge (16 or 18) short wire to ensure a better connection, just make sure it does not contact the terminal at the bottom of the socket. If you look at the socket you can see that there's a connection tab opposite the one I inserted the wire into. So you could probably use anything that fits in the gap between the bulb and the socket (e.g. toothpick, or the end of a plastic tie wrap) to push the bulb into a good connection at the opposite tab.

In any event, after making this modification I have resolved my random "right brake light malfunction" failure indications. Good luck !

[andresmit13]

Hey guys. I have the same problem but think the issue is something else.

I have a 2014 BMW F33 435i and also got the Left Brake Lamp Malfunction (not sure if it started when my battery got drained.) Anyways, it is just the left brake light and nothing is burned on the connectors so that seems fine and I've tried different tail lights as well.

I then also tested the volts and can't get a reading from the brake wire. Does anyone have an idea of what it could be? I've looked for any wire that is broken but can't seem to find one. (Also checked the fuses)

[Billfitz]

If there's no voltage on the wire and it traces OK to the REM then the REM may be at fault.