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Thread: Explain the Headlamps, please

  1. #1
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    Explain the Headlamps, please

    There are outboard and inboard headlamps, I have one headlamp on the inboard, right side, that is not working. It has continuity but no voltage at a time when the inboard lamp on the left side is working.

    Back in the days of old, the inboard lamps were for the high beam operation, but I pulled can pull and push on the turn signal stalk and this does not affect the lamps at all. What makes the inboard lamps turn on? It's something automatic because I can move my car a few feet going into or coming out of my garage and the left side will turn on. While the left side is on, the right side is still off and there is no voltage.

    I have cover off and looked inside of the headlamp pots, there is a lamp way in the back that comes on on both sides, it appears to make the rings around the edge of the headlamps illuminate (it's a low wattage, that I cannot reach). There is another lamp that is straight down that is an H3 55W that has continuity on both sides of the car but no power on the right side. There is a single YEL wire to it (same on both sides of the car).


    WHAT IS THIS BULB FOR AND HOW DO I TURN IT ON? And, is there a separate fuse, which one?

    There is something I'm not getting about the headlamps and the LCM and programming and all of that sort of stuff. My head is far to simple for my car, and this is starting to be a problem. I have never owned a car that was smarter than me....



    I am so confused.... I set up a mirror so I could observe the headlamps with different gear selections. The inboard lamps are Daytime Running Lamps, then come on when a gear is selected, but in R both of them come on but in D only the left comes on. That's not entirely true, there are instances when both come on in D, but I can't determine what those instances (conditions) might be. Why would a DRL only light on one side (driver side in the USA). I thought I was chasing a fuse, well I thought I had a lamp out but it tested good with my ohm meter so I moved on to checking fuses. I have a large mirror that I set up, and I can see that the lights work conditionally, so now I'm trying to figure out what the conditions are.

    Both of the inboard lamps come on in R, when they go off by shifting out of R or getting into full sun, they fade off -- they do not turn off, they fade to black. I'm confused by the whole DRL (Daytime Running Light) thing because they turn on when I shift to R but go out (fade out) when I shift to D. That's counter-intuitive to me, I would expect that DRLs would be on in D and full sun, but I drove down the street and back to my mirror, and the DRLs were off except when I shifted into R.

    I started today thinking I had a problem, but now I think I only have a misunderstanding of how it's supposed to work.
    Last edited by JDStrickland; 09-08-2020 at 02:50 PM.

  2. #2
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    I believe the inboard headlamps are the cornering lamps. If the headlamp switch is in the auto position, the left comes on when turning the wheel left. The right comes on when turning right. And they both come on when in reverse. There is no way to turn them on manually that I know of.
    ASE and BMW Master Certified Technician

  3. #3
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    Cornering lamps! Okay, that makes sense. I am getting one lamp (left side) when I came out of my garage, so I thought the other one was toast. I put the car in backwards so I can hug the wall on the right side, making more room to walk between the cars. I have to turn left to get out, so the left side light is always on and the right one is off. That's my symptom. I leave the LCM in the Automatic mode.

    So, I am dumber than a light bulb, that explains a lot.

  4. #4
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    Glad I could shed some light on the subject. Pun intended.


    Sent from my iPhone using Tapatalk
    ASE and BMW Master Certified Technician

  5. #5
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    You are correct, the lights I am asking about have to do with turning.

    What is the application? The only benefit they provide me while driving is in my neighborhood, but frankly they are not useful even there. I leave my LCM on Auto so the lights do what they do and I never have to think about them. In daytime foggy weather I turn on the Fog Lights to force the Low Beams on, and the headlamps go off when the key goes off so I don't think about the lights being on as I walk away from the car.

    Do you know what the engineers were thinking when they designed lights that the driver seldom if ever gets benefit from?

    If you know what they were thinking, what did they have in mind when they took out the Water Temp gauge and put in an Oil Temp gauge instead?

  6. #6
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    BMW engineers are bonkers. I work on these cars day in and day out, and it never ceases to amaze me the crap they come up with. Some of it is border-line genius (yeah, right), but most of it is absolutely asanine.
    ASE and BMW Master Certified Technician

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