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Thread: Headlight issue? Low beam failure

  1. #1
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    Headlight issue? Low beam failure

    I've search the forums but can't seem to find an answer. I have US-spec stockheadlights, but one of my low beams is out (passenger side). I've checked the light bulb and the fuses and everything is fine. Also, I believe the previous owner had different lights installed because the fuses have been upgraded to 10A. Anyhow, my thoughts are that its either the connector (it looks fine though) or the low beam relay. I would think the low beam relay would switch on both with one relay rather than each with two, but I don't know that for sure. Has anyone else had this problem? Thanks in advance.
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  2. #2
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    Quote Originally Posted by M3andPorsche
    I've search the forums but can't seem to find an answer. I have US-spec stockheadlights, but one of my low beams is out (passenger side). I've checked the light bulb and the fuses and everything is fine. Also, I believe the previous owner had different lights installed because the fuses have been upgraded to 10A. Anyhow, my thoughts are that its either the connector (it looks fine though) or the low beam relay. I would think the low beam relay would switch on both with one relay rather than each with two, but I don't know that for sure. Has anyone else had this problem? Thanks in advance.
    Swap the high and low beam relays.. if the problem moves with the relay then you know where your problem is. This is a common type of relay and any car parts store should carry one.

    Also check the wattage on your bulbs (it will be marked on them somewhere). If they are high-wattage bulbs you are really putting your wiring harness at risk. The stock wiring harness is barely adequate for stock 55w bulbs. Putting higher wattage bulbs in will not result in more light due to the voltage drop in the harness, and makes the wiring heat up.

    Best,
    Don Eilenberger
    '01 M-Coupe, '03 525iaT, '07 R1200R
    '06 Porsche Cayenne S - Titanium Edition (Iceland silver/Titanium

  3. #3
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    or just smack the headlight a few times it will come back on
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  4. #4
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    yup if its higher then 55w then it will heat up and melt check the inside of the plugs to make sure it looks clean and not melted.

  5. #5
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    Quote Originally Posted by inlinesixm3
    yup if its higher then 55w then it will heat up and melt check the inside of the plugs to make sure it looks clean and not melted.

    Not in my case. I ran 100w bulbs for 2½ years with absolutly no problems.

    I had a problem where one of my low beams would go out and i'd have to bump the headlight to get it to come back on but i never got a "low beam" warning when that happend. The only time I got the warning was when the bulb finnaly went out. You're sure the bulb you're "sure" of being fine is really ok? Why not swap another bulb in there and make sure it's not the bulb before you go digging for something else? Unless you actually tested the bulb and not just a visual inspection.

  6. #6
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    It's a stock wattage headlight bulb and I'm sure the bulb is fine. I swapped bulbs (left and right) and inserted a new bulb. No the connector is not melted or showing any signs of burning. I checked the connector last night and the power is getting to the connector and if I wiggle the connector I get the light to work. It appears to be one of the contacts in the connector is damaged. I'm going to replace the connector.
    Miscellaneous BMW parts for sale if interested please contact me.
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  7. #7
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    Quote Originally Posted by Mantic
    Not in my case. I ran 100w bulbs for 2½ years with absolutly no problems.
    Out of curiosity - did you ever measure the voltage drop between the jumpstart-terminal under the hood and the bulb (with the lights on)?

    You can do this with a simple voltmeter.

    With stock 55W bulbs, I've measured close to 1V drop. Doesn't sound like much, but it results in about 15-20% less light from the bulb. That's enough to be noticeable.

    All the 100W bulbs I tested actually weren't. They usually measured around 80-85W. I didn't measure voltage drop on the stock harness with one since I didn't want to damage the harness, but it wouldn't surprise me to see more than the 1V drop, and if so - the light isn't producing all the light it is capable of.

    Quote Originally Posted by Mantic
    I had a problem where one of my low beams would go out and i'd have to bump the headlight to get it to come back on but i never got a "low beam"
    warning when that happend.
    This sorta makes me question "absolutly no problems" - sounds like a connector going bad, which usually is caused by heat.

    Quote Originally Posted by Mantic
    The only time I got the warning was when the bulb finnaly went out. You're sure the bulb you're "sure" of being fine is really ok? Why not swap another bulb in there and make sure it's not the bulb before you go digging for something else? Unless you actually tested the bulb and not just a visual inspection.
    Actually - he found it was his connector, so it's possible a former owner went the higher wattage headlight route, or the marginal BMW harness is just showing it's colors as it ages.
    Don Eilenberger
    '01 M-Coupe, '03 525iaT, '07 R1200R
    '06 Porsche Cayenne S - Titanium Edition (Iceland silver/Titanium

  8. #8
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    Quote Originally Posted by deilenberger
    Out of curiosity - did you ever measure the voltage drop between the jumpstart-terminal under the hood and the bulb (with the lights on)?

    You can do this with a simple voltmeter.

    With stock 55W bulbs, I've measured close to 1V drop. Doesn't sound like much, but it results in about 15-20% less light from the bulb. That's enough to be noticeable.

    All the 100W bulbs I tested actually weren't. They usually measured around 80-85W. I didn't measure voltage drop on the stock harness with one since I didn't want to damage the harness, but it wouldn't surprise me to see more than the 1V drop, and if so - the light isn't producing all the light it is capable of.

    This sorta makes me question "absolutly no problems" - sounds like a connector going bad, which usually is caused by heat.



    Actually - he found it was his connector, so it's possible a former owner went the higher wattage headlight route, or the marginal BMW harness is just showing it's colors as it ages.
    The terminal on the bulb had corrosion on it, that's why it would go out every now and then. I figured that out when I replace the bulbs (Orsam Silverstars, are great ). As far as measuring voltage drops ect... No I havn't, I bought the car with the 100w bulbs in it and only noticed they were 100w when I replaced them.

    In anycase, it looks like he has the problem figured out.

  9. #9
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    Sorry to bump an old thread up, but it pertains to a problem I'm having. My headlight bulb connector has melted (the connector on the car's wiring side), and I can't find a replacement anywhere. Does anyone know if I can order one over the internet (or if anyone knows of a North Bay Area source)? The closest wrecking yard to me is about 1 1/2 hours away, and I'd prefer to find a new one anyway. It's #2 below, but the dealer couldn't find a connector even close to it:

    http://www.realoem.com/bmw/showparts...90&hg=61&fg=15

    Thanks for any help.

  10. #10
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    Quote Originally Posted by 95BMW//M3
    Sorry to bump an old thread up, but it pertains to a problem I'm having. My headlight bulb connector has melted (the connector on the car's wiring side), and I can't find a replacement anywhere. Does anyone know if I can order one over the internet (or if anyone knows of a North Bay Area source)? The closest wrecking yard to me is about 1 1/2 hours away, and I'd prefer to find a new one anyway. It's #2 below, but the dealer couldn't find a connector even close to it:

    http://www.realoem.com/bmw/showparts...90&hg=61&fg=15

    Thanks for any help.
    I don't remember exactly where I got mine but it was either at Wal-mart or Autozone. I think it only cost a couple of dollars. It was a pig-tailed connector that I solder in place.
    Miscellaneous BMW parts for sale if interested please contact me.
    - Victory RTAB tools (older style) - $75 shipped
    - OEM wiper blade refills (7 boxes) - $30 plus shipping.

    - M3 5spd tranny (pickup only - $500)
    - stock M3 sway bars (pickup only $40)
    - M3 front and rear calipers - need rebuilt

  11. #11
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    Quote Originally Posted by M3andPorsche
    I don't remember exactly where I got mine but it was either at Wal-mart or Autozone. I think it only cost a couple of dollars. It was a pig-tailed connector that I solder in place.
    Thanks alot. I'll try Autozone today. Didn't think to try there, 'cause they're usually worthless

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