Mike94ZLT1

iTrader: (3)

I am swapping an LS1 and a T56 into a 1957 Chevy. The LS1 is out of a 2004 C5, and the T56 is out of a 2006 GTO. My question is... is there a separate engine harness for the C5, or is it integrated with the rest of the vehicles harness? I want something to be able to control the engine, but not have to worry about other sensors and whatnot elsewhere on the car that I will not be using. Would I be better off getting a harness and PCM out of a 99-02 F-body? Thanks!

55chevy

iTrader: (6)

Yes, there is a seperate engine harness for the motor itself. One of our sponsors, John Speartech, specializes in FI harnesses. http://www.speartech.com/

You can also purchase other aftermarket harnesses from painless and many others but I don't think you will get the support that John can provide.

One thing that I would suggest if want to keep your engine compartment neat, is to get a extra length harness so you can hide the pcm somewhere like under the dash.

Mike94ZLT1

iTrader: (3)

What needs to be modified when using a factory harness? I don't understand what the $450 to modify the factory harness is for.

LS1 Coupe

I just sent out my 04 gto harness & ecm to wait4me performance, costing me $320 to have them pluck out all the crap, and set it all up for a neet little package for easy installation, they are also reprogramming the ECM for my grars and mods and also taking out all the stuff that isn't needed. The price includes all of these plus the return shipping back to me. I figured they have far more experience than I do with this setup, I could have done it and saved a few bucks but this is also knocking off 2 birds with one stone for about the same price as having a mail order reprograming done cover mods, eiminating any codes that will get triggered, gearing, tire changes, etc.

Ackattack1

iTrader: (7)

I haven't done this yet (my harness is in the mail) but I'm planning on doing it myself. Between the information you can learn about on here and by studying a wiring diagram and asking more questions on here I think its very possible for the average joe to modify thier own harness.

I also already have HPtuner, so that isn't a problem. I also have a few examples of the wiring I'll be running (05 silverado, 99 vette, 98 T/A) so between all of this info and looking at the examples...particularly the silverado, I'm pretty sure I can figure out how to wire up my 5.3L for my 68 truck.

The flip side is, what is your time worth? I'm sure it's going to take me quite a few hours to do all of this, but for a couple hundred dollars it can all be done for you. But, for me it's more about doing it all myself and figureing it out. That's also why I'm going to rebuild my own tranny, do the body work, and paint it myself.

Mike94ZLT1

iTrader: (3)

Well that's the thing... it's not like I've never seen an LS1 before, hell I've owned 3 heavily modified (by me) LS1 vehicles and I have my C5 still to use as reference if somehow I manage to get lost, but I think the wiring harnesses on these cars is easy! I would much rather do something myself than pay someone to do it.

Stu Cool

iTrader: (13)

Check the FAQs and Stickys at the top of the page. There is some in there about doing your own wiring. As was said, if you have the time, patience and confidence you can certainly do it your self. The main thing is eliminating the things that you don't need, and knowing what those are. Then putting the harness together with all the lengths that you need for placement of the PCM. Fuse panel, relays, ODB II connector, check engine light and 02 sensors. Then wrapping it all up in a nice neat compact package. One place to consider placing your PCM is up inside your fender, that's where I put mine and your '57 should have a nice space for it there too. I went with Speartech becuase I had no knowledge of the LS1 witing and computer. I had him build a harness for me from scatch with all the key lengths custom. It was totally marked and plug and play. My motor fired and ran on the first revolution and has been trouble free for 1.5 years and over 5k miles.

Are you going to keep the Corvette ETC (drive by wire)? I added that to my F-Body motor and love it! John wired me up for cruise control too.

Good luck on your project

Pat

jannes_z-28

I did the rewiring myself on my 2001 Camaro LS1 engine.

I went the route of getting the "carside" of connectors C100, C101, C105, C220 & C230 wich are the only connection points for the engine harness to the rest of the car. I got these from a friends donor car (he bought a complete harness) and got the connectors with plenty of wire lenght.

I had to change one wire in one connector to make the tach work, see:
https://ls1tech.com/forums/conversions-swaps/784870-solved-stupid-tachproblem.html

Beside that it was just a matter of connecting wires to fuses and relays and following the diagrams that can be found in the "Stickies"

If you're not "wirechallenged" it is just a fun project to do.

Good Luck


Jan

uncle ray

tell you what looks bitchin is the ls1 with a carb on top! if i had a classic chev that would be my set up!!!

rubrhammer

iTrader: (5)

I'm in the process of modding my own harness. I've used a lot of info from the stickies to learn what wire does what. I have taken my time with the tunes on and the laptop beside me and it has been an interesting project. W4M will be my choice for the ecm mod. I'm ready to connect to a power center and just scored one Thursday.(free) However, it is for a 98 s10 Blazer and my harness is from an 05 Siera. This means my next task is seeing if I can make them compatible. The plug fits I just need to arrange my wires to suit.
BTW, I never did any wiring before either.
Good luck and go for it.
Bob