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Hot Rods Lit Fan Toggle Switch

Discussion in 'The Hokey Ass Message Board' started by Markusohreallyus, Apr 27, 2019.

  1. Markusohreallyus
    Joined: Aug 1, 2011
    Posts: 57

    Markusohreallyus
    Member

    Hi, I want an LED-lit toggle switch to override the temp sensor to the relay (just in case)-can anyone point me to a toggle switch (make, number or...how to wire?) that does this:
    1) LED lights up when temp sensor on motor kicks the fan on (I’ve got a ground between the relay (#85 in my Rebel 9+3) and my current 4-post, SPST switch... AND:
    2) LED lights up when I flip the switch to manually override the sensor signal (e.g., in advance to sensor signal).

    In other words I want that LED lit whenever the fan is “on” regardless if it’s in auto or manual override (and “off” if the fan is off).

    Thanks!
     
  2. olscrounger
    Joined: Feb 23, 2008
    Posts: 4,774

    olscrounger
    ALLIANCE MEMBER

    I wire a small led light behind the speaker grill in 40's that comes on with engine heat switch,ac switch or manual override switch.
     
  3. TrailerTrashToo
    Joined: Jun 20, 2018
    Posts: 1,293

    TrailerTrashToo
    Member

    My search, a few years ago, was a failure. All the illuminate toggle switches (both incandescent and LED). were SPDT. To get the switch to light, the opposite terminal was grounded. The toggle switch, in the "OFF" position, was grounding the "LOAD" terminal. Instant popped fan fuse.

    Unless someone locates something different, a separate LED indicator is indicated (horrible pun...).
     
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  4. BamaMav
    Joined: Jun 19, 2011
    Posts: 6,759

    BamaMav
    Member
    from Berry, AL

    I wired one up once with it being on only when the fan was operating. Going down the road one night, I noticed the switch light was on, but the switch was off, wtf? There was enough airflow through the radiator the fan blades were turning, becoming a mini generator.
     

  5. Markusohreallyus
    Joined: Aug 1, 2011
    Posts: 57

    Markusohreallyus
    Member

    Thanks guys. I’m not sure, but I think it might require a diode or capacitor (goes to show what I know- one of those things with different color and number stripes) soldered between two posts to prevent backflow or ???? I guess it’s just one of those things I won’t worry about...
     
  6. Mike VV
    Joined: Sep 28, 2010
    Posts: 3,040

    Mike VV
    Member
    from SoCal

    Mark -

    The internet is a huge place... Start looking..! Find what lighted switch you think you want and install it..! Maybe buy two or three different ones.
    YOU need to do this search, others have their stuff to do too.

    Mike
     
  7. scrap metal 48
    Joined: Sep 6, 2009
    Posts: 6,079

    scrap metal 48
    Member

    Things were so much simpler when mechanical fans were used....
     
  8. TrailerTrashToo
    Joined: Jun 20, 2018
    Posts: 1,293

    TrailerTrashToo
    Member

    Just enough misinformation to be dangerous. The device you are thinking of is a diode, it gets installed in series (i.e. cut and inserted in the wire to the fan). After all that, the diode will block the 12 Volts, from the energized fan, from getting back to the illuminated toggle switch.
     
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  9. Markusohreallyus
    Joined: Aug 1, 2011
    Posts: 57

    Markusohreallyus
    Member

    Already did all that, and now depending on you experts. Thanks for your two cents.
     
  10. Markusohreallyus
    Joined: Aug 1, 2011
    Posts: 57

    Markusohreallyus
    Member

    So where do I get the diode, how many and what color stripes etc.?
     
  11. Markusohreallyus
    Joined: Aug 1, 2011
    Posts: 57

    Markusohreallyus
    Member

    Thanks
     
  12. TrailerTrashToo
    Joined: Jun 20, 2018
    Posts: 1,293

    TrailerTrashToo
    Member

    Let my try again - A diode simply will NOT work for a illuminated toggle switch installation. It is the electrical equivalent of a one-way check valve.

    Install the diode in one direction, the power flows to the fan, but will not light when the fan is powered from other voltage sources.

    Install the diode in the opposite direction, and the diode blocks the flow of power, thru the toggle switch, to the fan.

    You need to wrap your head around some electrical theory, and then verify your your wiring and toggle switch positions with a multi-meter. And install an appropriately sized fuse in the wire to your power source.

    At age 74, I still occasionally "operator-head-space" an automotive rewire and pop a fuse.
     
  13. Markusohreallyus
    Joined: Aug 1, 2011
    Posts: 57

    Markusohreallyus
    Member

    I wuz kinda thinkin dat. Thnx agin.
     
  14. Any switch with a LED indicator is wired internally and you will not be able to control the LED separately from the switch. May be possible to disassemble the switch and wire the LED externally but I doubt any common switches would be of the quality that would permit that without destruction.
     
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  15. Some LED lit switches have the feed wire to the LED spot-welded to one of the terminals, so if you are careful, you can snip the wire and join a bit on, that gives you access to the LED. A 1N4004 is a 1 amp diode, but if you are switching a relay, you shouldn't need a diode, as the contacts will be open circuit, therefore you can't get any generated voltage back into the system. (An LED -Light emmiting diode - is just that- a diode, so will only light up when forward biased, and will be a high resistance when in reverse)
     
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