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What relay to tap for kill switch?

Discussion in 'Engine & Drivetrain' started by Texasdaddy, Apr 6, 2020.

  1. Texasdaddy

    Texasdaddy Full Access Member

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    Looking to install a kill switch on my 18 LT. What wire do you recommend tapping that cant be quickly bypassed? I have heard fuel pump, ignition, and ground. Any danger to electronics with these?

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  2. wjburken

    wjburken Supporting Member

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    I think the fuel pump is a common circuit used with kill switches.

    @swathdiver might have some ideas as well as @Doubeleive. They have been discussing anti-theft ideas on another thread.
     
  3. swathdiver

    swathdiver Full Access Member

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    I looked at the wiring diagram for my truck and think the wiring from the fuel pump runs directly outside and under the cab to the ECM. I can probably tap into it near the firewall and run wires into the cab and to a switch somewhere. Still thinking about it.
     
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  4. Doubeleive

    Doubeleive Supporting Member

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    there are several ways, one way would be to just go under the fuse box and put in a switch for the starter fuse or fuel pump, you could do one for the neutral safety switch on the trans mission. just need a good wiring diagram and a idea of where you want to hide the switch. you can do it right under the dash at the bcm also if you know which wires control what. the gm upfitter guide should have bcm diagrams.
     
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  5. Bob2C

    Bob2C Full Access Member

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    My 18 Tahoe has the fuel pump fuse in the engine compartment block. It’s #22. Or you can use the run/crank relay located on the inside left panel. It’s #53. All the info is in the manual. There different ways to work it.


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  6. Texasdaddy

    Texasdaddy Full Access Member

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    Perfect! Seems the thieves all have same MO. Pop hood from under car, replace ecu under hood, pop door lock, pop plastic column off to get to ignition, start er up and drive off. Im looking at maybe adding hood or ecu lock somehow as well. Never had worries until 2 new silverados stolen in employee garage...

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  7. BG1988

    BG1988 Full Access Member

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    i think something better would to turn on all of the warning lights flashing check engine service 4x4 service traction control service flashing low tire etc.. flashing brake light
     

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