Planning on buying and using the Holley Terminator X on my 5.3 swap. I’ve pulled the motor and trans and now I’m down to figuring out what wires I need to keep under the hood from the old 305tbi harness. Obviously I need to keep the part of the harness for the lights and heater, but is there anything else in there that I should keep? Thanks for any info.

 

Through the c100 connector you have a tach wire, fuel pump, power (feeds power to the inside fuse block), starter. temp sensor. There are some ignition hot wires etc that you will use depending on how you wire the car to power the holley set up.

Get the c100 diagram for your car and go through it and decide what to keep.

http://www.austinthirdgen.org/?pid=19

The heater/AC wires are separate and come through a sub harness on the passenger side. If you are keeping AC you will have to decide how you are going to wire it.

 

Also, use the C100 to your advantage. Instead of just removing the wires from the C100 connector you can leave them (shorten or lengthen if needed of course) and run them to different items. For instance you could run an Oil temp gauge through an old unused emissions control wire. Many options.

 

Thanks for advice, I’ll download the wiring and see what’s necessary to keep.

 

Read the LS swap guide, the beginning part is relevant to almost any swap.

Good point, but even better than that is to just remove the terminals from the connector so they aren't cut, and aren't in the way anymore. They are very easy to remove from the engine side harness.

 

I just went through this. You need to look at the pinout and use common sense for what should stay and go. Keep the red 12v cables, fuel pump, and couple others. Decide your end goal (tablet dash or retain stock) and go from there.

Don't forget to buy an alternator pigtail from holley with the resistor. You can pull ignition power from the c207 connector for alternator and the red 12v ingnition wire on the holley.

 

Currently working on a very similar swap with a Holley Terminator X. I'm confused on wiring on the engine bay side vs. under dash on driver's side.

Can I just essentially cut the whole harness out of the engine bay side?

 

Read the swap guide, ALL the answers are in there

 

You can cut out as much of the engine harness as you don't need. How about that for an answer? There are six ways to Sunday for how people wire their cars. Just start walking through the old engine wiring and ask yourself, do I still need this sensor or part?

My HP EFI is very similar. You can get some ideas from post #1 of my build thread, https://www.thirdgen.org/forums/ltx-...-qwktrips.html

Regarding sensors that operate dash gauges, you'll abandon the old sensors and electrical connectors, but you'll keep the wires that go to the dash and merge it back into your new engine harness.