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LED charging light help

Discussion in 'Off Topic Hot Rods & Customs' started by topher5150, Feb 2, 2026 at 9:15 AM.

  1. topher5150
    Joined: Feb 10, 2017
    Posts: 3,787

    topher5150
    Member

    Trying to keep this simple I'm using a Ford 3G alternator on my build and a LED idiot light. Someone suggested that I use a relay to act like a resistor. Just wondering if anyone help how that gets wired togehter.
     
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 60,079

    squirrel
    Member

    connect the coil of the relay to the two wires that would connect to the light bulb. Then connect the LED to the NO contact on the relay, and connect power to the COM contact.

    I would use a light bulb, because that's what it's designed to have. You could put the light bulb anywhere hidden, and you might even be able to connect the LED across the bulb so you have an indicator that the bulb is lit.

    LEDs are great for many things, but old cars is not one of them.
     
    leon bee likes this.
  3. topher5150
    Joined: Feb 10, 2017
    Posts: 3,787

    topher5150
    Member

    85, and 86 from the green alternator wire
    87 NO, 30 COMM to the LED
     
  4. Damon777
    Joined: Jan 7, 2022
    Posts: 181

    Damon777
    ALLIANCE MEMBER

    I am in a similar situation with my 10si. My issue is actually finding an incandescent indicator.

    If a guy wired an LED and a standard bulb in, I would think that the LED would need to be in series with the light bulb, as the LED would provide a path of zero resistance if wired parallel, correct? Granted, it should work parallel if you got the polarity on the diode right.
     
  5. leon bee
    Joined: Mar 15, 2017
    Posts: 1,365

    leon bee
    Member

    Cycle parts places have a lot of different little indicator lights.
     

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