Mike Gatzke

I'm putting a ls 6.0 liter in a square body.its out of a 02 2500 with a 4l80 trans. Im running feul injection and need to know what to do with the wiring harness that was in the truck to make it work on the swap.

Haggar

Could you be more specific?

Do you have the engine wiring harness, and are wondering how to connect it to the truck harness?

Step 1: Find a good wiring diagram for your truck
Step 2: Look at the wire in the truck harness, and determine which ones you need to interface with.

Engine harnesses are usually pretty stand-alone. You'll need constant battery, switched battery, ground for sure. You may have some wires for lights or gauges in your cluster that you'll want to tie to the new engine. You'll need to figure out your starter wiring from the truck to the new engine... etc, etc, etc..

LS BRAVADA

iTrader: (4)

lt1swap.com

hokeplaya05

iTrader: (3)

you have to be way more specific then saying "square body". that could mean any GM truck from 1973 up to 1999.....

either way, there is TONS of info on this site and others about LS swapping any of those generations of GM trucks

LetsTurboSomething

http://www.lt1swap.com/2000harness.htm

This page contains 100% of the information you need to modify the 6.0 harness yourself or send it to him to have him do it. He is very reputable, is on this site, has probably more experience with harnesses than anyone else around here. I used his instructions and did mine, worked perfect. But that's not your question

I did a 5.3 into a '84 square body. You need practically nothing from the old system in there. You can keep the main positive battery wires that go to the alternator, distribution block on the firewall and the starter wires. The purple wire is the solenoid trigger for the starter there are two pink wires too the same gauge as the purple wire. Those two pink ones are keyed 12v wires, one powered the coil and distributor and one powered something else i can't remember. I kept one of them and used it to power the main fuse block and the power for the relays and fuel pump. You can trace out the idiot light wires in the dash and reuse them for the check engine light or what ever. I pulled the plastic lens off mine and stuck my boost gauge, AFR and meth controller in them. Left one for the check engine.

But the purple wire for the starter solenoid and one pink one for keyed 12v is all you NEED to keep. Run a 12v constant for the VCM and fuse block from the power distribution block. You can repurposed the rest if you're cleaver and want to.

JayinMI

Some other helpful resources I've found were on Youtube. Ucandoit2 has a very helpful series on slimming down an LS truck harness.
A21Bravo has some good info too.

Jay

NCDEERE

iTrader: (1)

You should also keep your alternator wiring and hook up t the new alternator. You can adapt your oil pressure and temp senders that match your gauges to the 6.0. If you have a mechanical speedometer that will have to be worked out.

CattleAc

iTrader: (7)

Super easy, I used an electronic speedo\gauge cluster, from a 1991 suburban square body...