heres the story a buddy of mine has an 89 iroc was originally a 350 tpi car he switched it to 400 with a carb blew that now he wants an LS swap my question is the factory tpi harness is no longer would it be easier to find another tpi harness and piggy back the ls harness of that or how would u go about wiring the motor any help would be great thanx

 

Not all, but nearly all LSx's for sale come with the harness and/or PCM...
but if it dose not, you could ask someone (Pocket) to make one for you or buy one from painless (among other vendors).

if your looking to convert the stock harness to a swap harness look here
https://www.thirdgen.org/forums/ltx-...rt-finish.html

 

ok if i go that route just using an ls harness how does the cluster and fuse box get tied thanx for ur advice blakecharles

 

The LSx senders and outputs are used to drive the factory gauges. Factory fuse points and reused. The thread and other corresponding threads go into detail what goes where and how you accomplish this

For the base 3rd gen harness you can use any engine type as long as its from a similar year. Sorry but you're buddy is stuck using an 89 harness as those are unique. He can use V6, TBI, TPI though

 

Pocket, could a 04 ctsv harness be combined with a 91 rs harness, or should I find an fbody ls harness?

Thanks

 

If you go the method laid out in the how-to thread, any LSx harness can be used. Fbody, Corvette, truck, cadillac etc. You're breaking it down for parts universal to LSx engines then rebuilding it using said parts to fit a custom application

If you wont be tearing it down to the basic elements and building it up, rather going for a minimal hassle install just repinning the body connectors, Id say yes, you NEED a 99-02 Fbody harness matching your trans type. Of all the LSx harnesses that fits the closest, but even those leave alot to be desired from aesthetics and redundant circuits