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Bypass inertia switch

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Old 09-16-2018, 05:25 PM
  #1  
importsmasher
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Default Bypass inertia switch

I put an 89 5.0 in my wife's 66 Mustang. I used the factory engine harness and computer. I'm almost to the point of firing it up for the first time, but the fuel pump isn't kicking on. It occurred to me that the original car would have had the inertia switch in the trunk. Obviously, I don't have the switch or its wiring harness. I presume I need to bypass this in order to make the fuel pump kick on? Can anyone tell me what wires I need to connect together on the engine/computer harness? Anyone have a wiring diagram?

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Old 09-17-2018, 02:29 AM
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08'MustangDude
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If you can find the two wires that go to the inertia switch, you just connect them
together. I do not know that the colors are for your year...
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Old 09-20-2018, 09:50 AM
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importsmasher
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That's what I was hoping to find....someone who could tell me which wires to jump together or who could provide a wiring diagram so I could figure it out.
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Old 09-20-2018, 03:31 PM
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Urambo Tauro
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Depends on how much of the '89 harness you have. You've got the engine/computer harness, but not the inertia switch... what about the fuel pump relay and its wiring? Do you have any of that stuff? How is your fuel pump wired?

Veryuseful.com is a pretty good source for diagrams. If you scroll down this page to where it says "Schematic, in color, of the Fuel & Alternator & Ignition & AC, for a 5.0", you'll see the inertia switch between a red and a red/black wire. I don't know if you have those color wires, but the rest of the diagram should point you in the right direction.
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Old 09-22-2018, 06:42 PM
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importsmasher
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Urambo Tauro, thank you! Those wiring diagrams were exactly what I needed! Turns out I missed the wire that provides battery power to the fuel pump relay (and the computer for that matter). Hooked it up, and was able to start the car for the first time in 5 1/2 years!

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Last edited by importsmasher; 09-22-2018 at 06:43 PM. Reason: Typo
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Old 09-23-2018, 12:13 PM
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Ah, that'll do it. Good to hear it was an easy fix!
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Old 09-29-2018, 01:44 PM
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Oops I was too late. Glad Urambo got you taken care of.Glad to hear its running.

Last edited by wbrockstar; 09-29-2018 at 01:51 PM.
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