1965 MMP's Barracuda Hemi swap! The Ever Changing Build

MonkeyMadness said

Okay hit a bit of a snag last night, the efi system requires two lines wired into the starter switch one is (start) and the other is (run/start) which this old of a plymouth does not have as an option. So just ordered a couple painless diodes from summit which I'll have tomorrow. These diodes will allow me to bride the gap between the key+ (run) output wire and the Key+ (start) output and supply the efi lean/harness a constant power with key on.

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Can you elaborate on this a little? I understand how the diodes would work so the run/start leg would only get power when in the key position. What confuses me is why you need it?

I've been working on my plans for my swap using an '09 Challenger PCM and while I don't think it has the wire in the harness and might need to be re-programmed to accept a start signal on a pin rather than over the buss, I think it is workable.

This would mean for me, I need to use a different ignition switch so my blue wire has a constant power and the PCM sees 12v in both run and start/run, and then I only need to feed power to the start signal pin using the yellow wire off my switch. This tells the PCM to start the motor and the PCM grounds the starter relay.

I can't figure out where 2 separate run and run/start circuits come in to this. Are you not using an NGC controller anymore? Maybe I missed something?