NEED HELP WITH AUTOMOTIVE LED BRAKE LIGHT!

Discussion in 'The Projects Forum' started by UNEEKONE, Feb 1, 2009.

  1. UNEEKONE

    Thread Starter New Member

    Feb 1, 2009
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    0
    I am new to this forum but have tried to find what I am looking for with minimal success. I have a pair of LED tail lamps from an Infiniti FX45. When I first picked them up I was a bit surprised to see only two leads connected to the assembly's LED panel. I was expecting to find at least three: one for the running light, one for the brake, and the third for the ground. I hooked up a 12 volt source to the LED lamp and everything works perfectly. However, now I have no clue how to have these lamps work properly for both the brake and tail light functionality that I need. When I hook the lamps up to the 12 volt source the LEDs emit their maximum output... I am assuming that the Infiniti has a very complex system that varies the current/voltage in the wire to the lamp so that it functions properly. The vehicle that these will be modified to fit is a typical incandescent configuration with running and brake lights on the same bulb. So my question is the following: how do I wire these lamps appropriately so that I have two distinct phases; one for the tail lamp and one for the brake lamp? I would be extremely grateful for any and all feedback, suggestions, and/or information...

    Thanks!
     
  2. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    Cars use Pulse-Width-Modulation to change the brightness of running and brake LED lights.
     
  3. UNEEKONE

    Thread Starter New Member

    Feb 1, 2009
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    0
    Okay, so I am a little confused. The LEDs are super high output red-orange and there are 27 wired in parallel with zero resistors to be found. I am not 100% if these are some sort of propriety LED created specifically by/for Infiniti but it doesn't seem to fit all the circuits that I've seen out there. Please check out the attached pictures. The second picture shows the panel connected to a 12v source. Does anyone have any thoughts on this? Can anyone help me figure out the correct circuit to properly control the voltage with a regulator and figure out the PWM???
     
  4. renegade1957

    New Member

    Feb 21, 2009
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    i would not keep powering the unit directly as you have been. they are probably on the edge of failing if there is no resistance in the circuit. what is the red wire? is it a short piece of resistor wire or just a jumper? what value? also appears to be a twisted splice in second row from bottom between 2nd and third led from right, what is that?
    with a few snips here and there, you could divide it into 9 branches of three bulbs each with resistors to dim the branches you would use as running lights and diodes to isolate them from the brake lights.........good luck.
     
  5. ascari

    New Member

    Feb 26, 2009
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    Hello. You received the right answer from Audioguru... they use PWM.

    Read about it...

    Is simple to explain. Pulse Width means that the leds are ON for a while and Off for a while. when you start the lights of the car... they are (just to say an example) 10 ms ON and 15 ms OFF... and you see them as permanently ON but with a lower bright...

    When you hit the brake pedal, they are 50ms On and maybe 10 ms OFF then you see them with more bright.

    That means you are changing the Pulse Width.

    There you have the "optic" of lights on and brakes on.

    I hope I helped.
     
  6. renegade1957

    New Member

    Feb 21, 2009
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    i believe you have explained how the system would work in the vehicle that the leds came out of, however i think he is looking for assistance with installing them in an older vehicle that does not use pwm but rather the old style lamps and straight battery voltage................;)
     
  7. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    The Lighting control part of one of the onboard computers in an Infiniti, and often isn't available to use separately. However, if LED taillights were an option on your year/make/model vehicle, it may be a standalone module available for purchase.

    Some GM vehicles have the controller separate, here is a page covering the complete project of converting a Corvette to LED taillights, there are similar pages around as well.

    http://xse.com/leres/z06/led.html

    For this application, for safety from tickets, as well as being rear-ended, and other things that happen when the electrical system dies. I'd suggest purchasing a rated factory component instead of a DIY solution. The "drivers" seem to run in the $50 to $150 range depending on how many functions the LEDs perform (taillight/turn signal, brake, etc)

    To find out if LED was an option, and to get a used one from a recycled car (junkyard), check out http://www.car-part.com
     
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