Wiring Harness for the G3 Hemi Swap

[69Chrgr]

What are you guys using for a new wiring harness (aftermarket) to accommodate any extra circuits? I've been looking at AAW but would like to know what ya'll are using and your thoughts and opinions.

 

[racerjoe]

What are you guys using for a new wiring harness (aftermarket) to accommodate any extra circuits? I've been looking at AAW but would like to know what ya'll are using and your thoughts and opinions.

If the car has the original wiring harness, or a stock type replacement harness, my vote would be to add a secondary fuse/relay panel for the ECU and trans (if applicable). In order for EFI to work well without any problems, you need good grounds on the electronics so keep that in mind. At minimum, you will need relays for a fuel pump and fan(s). I ended up using a American Auto Wire Highway 22 kit for my car, because there isn't much besides the headlights and tail lights that are original. There was no sense in hacking a preproduction harness to accommodate the aftermarket gauges, HVAC, and EFI engine.

 

[darto]

I will be keeping my original style dash and under hood harnesses as they are only a few years old.
I will be removing the engine side of the under hood harness and use a Hotwire harness to run the ECU and transmission on my 6.1.
I’ll add a second relay and fuse panel for any other items such as gauges and fan controls.

 

[Map63Vette]

I went the crazy route and built the whole thing from scratch myself. I got several harnesses from my old job that were warranty returns (had a couple of melted wires, but 90%+ were fine) that I took apart and organized by color and gauge. Originally took my old harness out of the car and set it on the dining room table and traced new wires on top of it to rebuild with all new terminals and add some circuits for the new engine. Ran that for a while, but when I upgraded my Megasquirt 2 from fuel only to an MS3X running ignition as well I went the route of modern vehicles and made a dedicated engine harness that was separate from the chassis harness. So all the body stuff like lights, horns, fans, etc. stay on the factory bulkhead, but all the engine stuff (injectors, coils, sensors, etc.) went into their own harness and I drilled new holes in the firewall for new bulkhead connectors. The cabin side of the harness is a little more integrated though. I put in a whole new fuse box and fused more circuits than stock, plus added several for new things like the computer, my dash display, and some general accessory circuits. Amazing the difference new terminals make on stuff. Switches and stuff used to be kind of flaky and the lights might dim and brighten on and off, but everything is pretty solid now. I kind of need to pull my cabin harness out and clean it up now with all the stuff I've done since though. Mostly just bundling wires together better so they route more cleanly, but I'm always changing stuff it seems. I'll probably at least try to clean up the main trunk of wires that will go to my new center console if I ever finish building it.