Stock 4 Pin Ignition Switch Wiring

I am going over my documentation for the wiring side of my ECU (Haltech Nexus R3). A little background is I am completely rewiring the whole car, removing all the factory wiring and fuse boxes and relays. I am installing Haltech PD16 to control the vehicle systems. Now I know that the pin for the Ignition output goes to the ECU. My question is regardless of what I do I am still going to have to run a fused 12v source to the 12v (Battery Pin) on the ignition switch? is this correct to assume? otherwise there will be no output for the ignition side to turn on the ECU? also if I am running PD16's to control the body wiring and systems, where does my accessory wire now hook-up to? I know I can put the start signal output from the switch to the PD16 or ECU and assign an output from within the software.

Added a snapshot from Haltech wiring diagram

[img="blob:https://www.hpacademy.com/e5d3a358-a87d-4d0d-8585-03cac7e474b5" alt="" alt="" ]

The supply for the key switch would be powered by the +12V low current output, then the 3 outputs of the key switch can be wired to the ECU.

Their documentation states you can only use this for low current loads so you would only wire the ignition and start circuits back to the ECU. You could maybe get creative with using the ACC circuit of the key switch for the ignition input to the ECU then using an ECR function to power your accessory loads.

Configure the ECR output as one of your PDM resources if you want to power a radio when the key is in the ACC position, then configure a second ECR function activated by the ignition input to power the engine circuits like the coils.