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Troubleshooting e92 trunk light?

Discussion in 'DIY (Do-It-Yourself)' started by Cherney Bumer, Apr 19, 2016.

    • Member

    Cherney Bumer

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    Hey everyone,

    The interior light in the trunk of my e92 isn't working. Hasn't ever worked since I bought the car. Can anyone give me a run down of where I start to troubleshoot this? I'm a noob. This car has various electrical issues, heated seats don't work, drivers side bolsters don't work, steering wheel buttons, etc. Any help getting this fixed would be greatly appreciated, I'll be paying close attention to the thread
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    MGarrison

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    How long have you had the car? Production date? (mo/yr is on the sticker on the door opening) Any idea of the battery's age? Or, if you've had the battery replaced in the time you've had it, did the battery registration get completed? These cars get all kinds of wonkiness if the battery gets weak or if a new battery isn't registered.

    You can use realoem.com to look up parts and parts diagrams, which can sometimes be helpful in figuring out how things are assembled or might be removed. I don't know how the lens cover removes, but it probably either just pops out, or, has a spring at one end, and is pushed to one side or the other far enough to swivel out. Charlson can advise on that; once you can get access to the bulb, you can see if the bulb's burned out or check if there's power to the socket.
    • Member

    Cherney Bumer

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    I haven't had the car for long at all. I'm in the office so I can't check the door jam, but it's an 09. Not sure if the battery has been replaced or not. The car also likes to throw random errors, for example that my right brake lamp is out when it isn't, and my left adaptive headlight went out randomly and came back on when I restarted my car. I'll try seeing if the bulb is good, hopefully it's something simple like that. I'm trying to avoid taking the car to BMW and getting charged for small issues like this. Thanks!
    • Member

    MGarrison

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    With such a morass of issues, I'd be suspicious of the battery - see if it appears to be a BMW battery & looks old-ish, not sure if an original battery would have some kind of date indicator on it or not. I don't know if there is a much cheaper alternative for properly-done battery registration than the dealer (BMW-specific indie-shop maybe).

    The battery registration process essentially calibrates a new battery & it's properties, and all the car's electronics systems, to each other - if the battery is old & weak, various things don't get the voltages they're expecting, with resultant random electrical wonkiness. Unfortunately, there's no viagra-like equivalent for weak battery... although, if there was something similar, it would just be temporary, with potential unwanted side effects (call your dealer immediately if your car is still over 14 volts more than 4 hours after it's gotten Bav-agra) :D. Uh, anyway... I wouldn't be surprised if it's still the original battery, I think 6-7 yrs. is within expected battery lifespan.

    The downside - battery registration takes some time, I think usual charge is something around $300, and then there's the battery on top of that. Not sure of dealer battery prices, you could probably source the right Interstate battery from someplace and drop it in yourself and then have the dealer do registration. I would be puzzled if a dealer wouldn't register a battery you install, might be worth asking if there's any issue with that.

    Realoem.com is a useful reference for parts diagrams, part numbers, production runs, etc., but I think their price listings are like high-end of dealer msrp - you can comparison shop parts prices from a slew of places for o.e. battery prices, like Roundel advertisers, bavauto.com, google, etc.

    Charlson will have more insight on the battery as a possible culprit, or whether something else, perhaps alternator-related. Seems a bit unlikely to me you'd have all that happening without it being a symptom of a broader issue.
    Ken.S.330 likes this.
    • Member

    Cherney Bumer

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    I have a very good BMW indie shop close to me, one of my buddies also owns a speed shop that might know how to register a battery. I'll ask about that, thanks for the info
    • Member
    • Technical Service Advisor

    charlson89

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    First thing to check with the trunk light is to check the bulb and make sure the filament isn't burnt out. If the bulb is ok you will need to check power at the connector for the light. As for the other issues weird that you have this many electrical gremlins. Normally when you have this many electrical issues there is one cause but there always those one off cars they have multiple issues. Has this vehicle ever been in flood or salvage title?
    • Member

    Cherney Bumer

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    No flood that I know of, and clean title. I can explain some of the issues. The steering wheel for example is swapped out with the sport one, so I just don't think it was installed correctly. Not sure if the seats are swapped as well. The trunk I'm yet to really investigate, I'm probably going to have someone help me check the fuses tomorrow and see if I can fix something

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