*Probably* door puddle light blowing fuse - but kinda complicated | FerrariChat
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*Probably* door puddle light blowing fuse - but kinda complicated

Discussion in '456/550/575' started by asgor, May 16, 2017.

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  1. asgor

    asgor Formula Junior

    Sep 8, 2016
    714
    Virginia, USA
    #1 asgor, May 16, 2017
    OK, this is odd. I've had the "cabin + door lights and trunk" fuse (A15) blow sporadically in the past few weeks.

    After much observation I have determined that the fuse will blow occasionally right after opening the driver's door - but not always. I then remembered that when I bought the car it came inexplicably without the driver's door puddle light, and for many months the A15 fuse didn't blow UNTIL shortly after I installed that same puddle light, which I found in a small box of spares that I also obtained with the car from the previous owner.

    Thinking that the puddle light was shorting, I proceeded to order a new unit from Ricambi, and I installed it just a few days ago. All was well for a short while then, wham, the same A15 fuse blew again today.

    Oddly, if I remove the puddle light unit altogether (old or new) the fuse won't blow - I tried driving around without the puddle light for several days and no problems occurred with the fuse.

    Other than removing the puddle light for good and going around with a gaping hole on the bottom of the door (I am a bit meticulous and that just won't do for me), how should I go about troubleshooting this issue?
     
  2. Andrew D.

    Andrew D. F1 Rookie

    Jul 6, 2008
    3,979
    Goodwood Ontario
    Full Name:
    Andrew D.
    #2 Andrew D., May 16, 2017
    logically there is a short in the power wire to the light or a short in the button that responds to the door opening Check those two first.
     
  3. asgor

    asgor Formula Junior

    Sep 8, 2016
    714
    Virginia, USA
    #3 asgor, May 16, 2017
    Yes, I agree. But wouldn't a short like that manifest itself whether or not the puddle light is uninstalled? If the light is removed all is well, but if it is installed, bam! the fuse is gone (intermittently).
     
  4. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    36,965
    Cowboy Capitol of the World
    Full Name:
    Brian Crall
    #4 Rifledriver, May 16, 2017
    The button is typically the ground side so very little chance it is the problem. Most of those lights are exposed on the back side. I would consider something in the door coming in contact with the light fixture inside the door. Also, the fixtures typically do not protect what is supposed to be the ground side of the fixture itself. It may be if the wires are connected backwards to the fixture, assuming 2 wire connectors, it may be shorting for that reason.
     
  5. asgor

    asgor Formula Junior

    Sep 8, 2016
    714
    Virginia, USA
    #5 asgor, May 16, 2017
    Last edited: May 16, 2017
    Ha! I am no electrical engineer, but I thought (at least in this simple application) any wire could be connected to any polarity. Yes, this is a 2-wire connection: let me switch the wire connections around and I will report back.

    Thank you for the tip!
     
  6. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    36,965
    Cowboy Capitol of the World
    Full Name:
    Brian Crall
    #6 Rifledriver, May 16, 2017
    That is not what I was suggesting. One side is made to be the ground and the other the positive in most cases. Figure out which is which and correct it if needed.


    That is not the same as telling you to switch the wires.


    Please. If a little common sense is applied to the problem it can be fixed.
     

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