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Hella 500 question

Discussion in 'Lighting' started by riggsjt, Nov 20, 2009.

  1. Nov 20, 2009 at 12:10 PM

    riggsjt [OP] Well-Known Member

    Jun 7, 2009
    First Name:
    11 FJ Cruiser
    Want to start off with saying I am new to wiring, so saying that, if i splice into the running lights instead of the high beams will the lights work whenever i have the running lights on?
  2. Nov 20, 2009 at 12:25 PM

    jspadaro Well-Known Member

    Jan 7, 2009
    First Name:
    Knoxville, TN
    Former Tacoma Owner
    Blue Oval Mod
    Yes. But they will not be on if the running lights are not. You can also use a fuse tap if you want to simply be able to switch them on whenever your truck is on (what I did).

    Light wiring is pretty simple stuff. All the hella 500 wiring does is use a relay. basic principle is:
    The relay has 2 prongs that are a feed for power, say from your battery directly.
    The other two prongs are to control whether the first two are bridged.

    So you have what you want to turn on and off, presumably high power (55W in the case of hella 500's): the line goes from the battery to the relay on one of these prongs, and then from the other prong to your lights. The lights then need to be grounded.

    On the other end, you just need _some_ source of 12V current going to the 3rd prong. This can be fuse tap to some switch to that 3rd prong, and then from the 4th prong to a ground.

    The idea is that you really have two circuits of power here:
    POWER ------------> RELAY PRONG 1 | RELAY PRONG 2---------> LIGHTS -> GROUND


    POWER ------>Some switch->-------> RELAY PRONG 3 | RELAY PRONG 4 --------> GROUND
    (This power source is likely not the battery, though that would work. Typically you'll use say a fuse tap so the Power is coming from a source that is automatically switched on and off with the ignition)
    (The switch stops the power from your power source from triggering the relay if you want it off. If the power source isn't on, turning the switch on does nothing.)

    So all a lighting circuit really is is using one source of power of lower wattage, to trigger the higher wattage lights. A relay can be thought of as an electrically-powered switch of sorts.

    You could directly use a switch in place of the relay in the first circuit above, but this is bad practice because you're running 55W through a switch (likely in your dash). Directly using a switch is what you do for small stuff, though - like flashlights.

    The relay lets you have your high-power connected to one side, and turn it on and off with a very low wattage circuit on the other. If the connection across prongs 3 and 4 have power, the relay will internally connect prong 1 to prong 2.

    Hope that helped.

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