Need help with a simple electrical switch wiring

Discussion in 'Electrical Systems' started by gutted72, Jul 2, 2019.

  1. gutted72

    gutted72 Veteran Member

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    I am getting ready to wire up a kill switch to my fuel pump for a little piece of mind.

    I know how and where I want to put the switch but I need some help with the switch. There are so many switches I can't seem to find what I want and I'm probably over thinking it, but...

    When I wire in the switch I want to also wire up a LED so that I know when the power is on and when the power is off, the hard part is I want the LED on when the switch is actually off and vise versa. I know, why not just use a lighted switch, not that easy, the kill switch will not normally be accessible, so I won't be able to see it.

    The next obstacle is that the switch needs to be heavy duty enough to feed the power to the fuel pump, so around 30amps?

    Any suggestions would be great.

    Thanks.
    Wess
     
  2. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

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    First off, don't run a 30 amp circuit into the cabin, go low amp with a relay near the pump. Secondly, I don't know how you'll get a mini indicator light on when the switch is off, doesn't mean it can't be done, just I don't know how.
     
  3. gutted72

    gutted72 Veteran Member

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    So if I run a 12v power wire to the switch and then to a relay that will control the off/on power for the fuel pump. Now I just need to figure out the light.

    Thanks.
     
  4. gutted72

    gutted72 Veteran Member

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    This is how I'm thinking about wiring it up, but I'm going to use a push button instead of a toggle switch. Then I need to figure out the light. fuel-pump-kill-switch-diagram-without-steps.png
     
  5. ULTM8Z

    ULTM8Z Veteran Member

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    The center terminal on the relay (87A I believe) should be powered on when the relay is off. I think it's the "normally closed" terminal. If you hook up the light to that terminal and to ground, it should go on when the kill switch turns off the fuel pump.
     
  6. dale68z

    dale68z Veteran Member

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    My thoughts.
    Use an an led light wired across the switch terminals. The switch will be turning on the ground for the relay coil (86). If the relay coil always has power on 85, the relay will also have power on 86 when the relay is off *unless the relay has a diode in it. So, when the switch is off, one leg of the switch will have power from 86, and chassis ground on the other leg of the switch.
     
  7. jamieg285

    jamieg285 Veteran Member

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    I'm with ULTM8Z, use a switch over relay.

    Your manual switch activates the relay. When the switch is off the relay output goes to the light, when on it goes to the pump.

    You'll need to make sure the power to the switch is linked to the ign circuit, so it's not on all the time.
     
  8. gutted72

    gutted72 Veteran Member

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    Thanks everyone. I will do a mock up tomorrow and see if it works before I start cutting wires.
     
  9. Scott51

    Scott51 Veteran Member

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    This should help http://www.rattlebars.com/mtz/basicrelay.html

    In your case use a 3 pole switch fed by an 'ignition on' circuit (eg. the ACC terminal on the fuse box) to trigger the relay in the ON position (terminal 86) and power the LED in the OFF position.
     
  10. gutted72

    gutted72 Veteran Member

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    Scott51,
    That was very helpful, thank you very much.
     

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