So as i get all my parts together for the 5.3/T56 swap, i have been reading about wiring since i think this will be the most tedious part, especially since i am not good at it at all. So i have a question that i searched for the answer to and maybe im just bein a complete jackass for asking but....

im using an 03 5.3 with all LS1 accessories bolted to it, eccentially it will be an LS1 minus the cubes, why cant i just buy a 99+ LS1 harness and plug the whole thing in and delete what im not using right from that? i mean, i really dont see the need to take apart the harness. if i delete the rear O2's, i delete the wire, etc etc. i wont be extending wires, ill run them under the heater box and tuck under the dash however best i can. I can really see a huge nightmare taking a harness apart and re-wiring everything, i would rather use the stock harness as it came for a plug n play deal with non-used wiring deleted off it and tuned out from the computer. No dis-respect to those who have done the re-wiring threads such as pocket, im just looking for an easier way that suits my wiring skills.

 

you could do exactly that as long as you stick with the fbody accessories and maf/iac. I believe everything else should wire up exactly the same.

 

thats what im thinkin Dan, i mean basically its a plug and play swap, like the gas tank issue, i figured if i want to use the tank why not use the stock fuel lines as well to save myself the wiring hassle and fittings etc making it as close to a plug n play swap as possible.

 

I went with an LS1 F-body harness with my swap and everything is the same except for the oil pressure sensor, it had a different plug. Idk if this will be the case on yours but you could either splice the correct connector on there or you can change the sensor to the correct one. It would actually be easier to use a harness out of an F-body that had a T-56 since all the wiring for the manual trasmission is already there and the truck harness has all the wiring for an automatic trans. When I had my 411 computer tuned, I had it tuned for a 5.3L with camaro injectors.

 

Dyno, thats exactly what i planned on doing, an F-body LS1 harness from 99-02 from a T56 car. Thanks for the response! im feeling better already. So since you used camaro injectors do they run at a diff. PSI? (higher?) i would almost think it would be better that way if you have a ram air set up/CAI with full exhaust and getting some extra fuel from the larger injectors at WOT to match the combo...?

 

I believe the injectors flow ratings may have been different between the years but i'm not 100% positive, good luck with your swap man I've been driving mine now for about a week and I love the driveability as far as gas mileage, etc. The 5.3 is still a pretty stout little motor and i'm sure you'll be happy you went this route, I certainly am.

 

Got another one and ive been reading posts for 4 hours...lol. what exactly do i need to wire in if im using a 99 T/A LS1 T56 engine harness concerning the dash/body harness. im using the exact engine harness so its as close to a plug and play swap as possible but since i totally suck @ wiring, im not sure what everything i read means... Do i have to locate 8 or however many wires it was in the engine harness and run them to my existing 3rd gen dash harness? please, talk to me like a toddler...lmao

 

quoted:

"What you need to do is pretty straight forward: Connect the LS1 engine harness to your third gen stock Chassis harness. To do this you will need the pin outs for both your car and your engine. It only takes 6-8 wires to connect together to make the engine start and run. The rest are simply to make your accessories work like gauges and A/C if applicable, etc. The challenge is just weeding through which of the 8 wires to connect. Worst case scenario is about 25-30 splices if you have a carb car to start with and keep A/C and all accessories. Here’s a quick breakdown of the process;"

Easiest access to these wires?? i know thats like handing the work to be done on a silver platter.

 

If you want to do this right and learn it correctly then I highly suggest buying a service manual. Not a chilton or haynes but an actual gm service manual. I bought mine on ebay for $120 so be prepared to invest some money in it. The payoff will be huge. The reason I suggest this is because of the wiring diagrams. You will never find better wiring diagrams then in a service manual.

Your next task will be to learn how to read a wiring diagram. Start now on the internet before you get your manual. Learn the basics like what symbols stand for on the diagram and how a relay works. You need a good foundation before you dig into wiring.

Wiring is actually very simple once you realize that electricity is a circle. You start with a power source or a positive side, then it flows through some type of power using device, next it goes to ground, from ground it goes back to the power source. Every circuit is composed of these steps. Supply, usage, and ground. Sorry to take this route but its better than saying read the stickies right!

 

Thanks FireHawk, i actually went looking for a service manual before i even started buying parts for this swap and i will definetly pick one up, not to throw this is anyones face but i know a guy where i can get service manuals for like $5 bucks a piece so if i get ahold of him and he has a few for 98-02 cars ill buy them all. i know the simplist basics about wiring. symbols i need to learn so i agree. thanks for your input... pretty sad im a certified GM and Mazda tech huh?? well.... those certs are all good except my tranny rebuild cert (2%) and wiring (10%) LMAO

 

First off, bookmark these two sites

http://www.lt1swap.com/wiringharness.htm
http://www.austinthirdgen.org/index.php?pid=19

All the in depth schematics are available for you in there. Read the threads a few times until you get the basic concept behind it:

Disassemble
Label
Group
Mock-up
Connect
Test
Install

You should also be going at it in two phases, converting the swap harness and then marrying the new harness to your 3rd gen harness in the end. Trying to do both at the same time will overload you

Also, the truck oil press sender connector should be the same as the LS1 Fbody. Both should use the standard single pin connector. Late 3rd gens also use a viable connector with 3 pins. Simply remove or just snip the extra two and it will fit the LSx sender no problem. The biggest difference in Fbody vs truck is the INJ/MAF and a ton of unused connectors. Fbody harnesses are pretty basic to begin with for a stock harness

 

My engine wiring harness is 100% plug and play, and I retained the LS1 fuse blocks so my relays and fuses were 100% as they were in the 4th gen. Made the fans and everything work perfectly.

I DID have to extend a few wires to make it plug in and have good plug placement... If you want the PCM under the dash, you probably will too.

Its not minimalist by any means. But it works great, and I think it looks fine. I only retained about 3 wires from my c100 plug...the rest I deleted.

J.

 

What did you guys use for injector size? im thinkin of going with 28.8's for future cam swap or engine swap and tune it, but will the 26's work? i might just buy both. thanks

 

99-00 26's can handle most cam swaps. Since they cost the same, going 28's from the start isnt a bad idea. Several guys are over 400rwhp on the stock 28's