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Discussion Starter #1
Finished putting in my momentary switch (which has to be held down while cranking the car, got the idea from the disarm switch on the crappy old Ford add-on alarm) but would like to add a simple DPDT switch to cutoff power to the fuel pump (relay?) and/or ignition coil power. However, I want to just cut in to a constant power supply and not anything that pulses or isn't a full +12v (like a 5v signal or something) and not sure of the location or wire colors under the dash or by the ECM that would work for what I want to do.

Suggestions on what to break into?
 

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Take a look at the inertia switch on the back wall/driver's side in the trunk. I'm not sure which wire to tap into though.

edit:
There are 2 wires, looks like pink/black goes from the inertia switch to the fuel pump. However, you could probably tap into either wire to disable the engine.
 

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Take a look at the inertia switch on the back wall/driver's side in the trunk. I'm not sure which wire to tap into though.

edit:
There are 2 wires, looks like pink/black goes from the inertia switch to the fuel pump. However, you could probably tap into either wire to disable the engine.
Yea in fact for that you could just use a single throw switch in series with the positive side and leave the ground alone (or do it with the ground and leave the power alone) either way it would work. I'd like to use something that keeps the engine running, and since the ECU modulates power to the fuel pump on 99+ cars, I wanted to avoid doing that. However, I did the exact same thing on my 88 5.0 and it worked great (tapping into the wire going into the inertia switch from fuel pump relay).

Speaking of which, is there a fuel pump relay under the seat on a returnless fuel system that I could just put a switch on the ground side or something of the relay coil? I assume even though the ECU modulates power for fuel, the relay (if there is one there) wouldn't do that
 

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The fuel pump relay is within the CCRM.....

Here are a couple diagrams for it. Use the 2nd one to trace the wire up that branches off to "M" to see where it goes.
 

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If you need this one, it should be where "B" goes to on the 2nd diagram.....
 

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