I cleaned up my wiring docs tonight. They're merged from a bunch of different sources, and go pin-by-pin of connecting to the LS1 harness, which was a lot easier for me to read than a schematic :). This is specific to the 1999 Fbody LS1 harness, but the 2000-2002 harnesses are close enough that you can probably figure it out. I also included all of the PCM programming changes I made to work with this setup.

http://www.blown.net/ls1swap/rodders1999ls1t56wiring.doc

Wow, gonna hafta to look at that when my eyes are open

Excellent info!! :thumbsup:

Cool, lunch time reading materials. Terrific stuff. I may want to pick your brain about the HPTuner soon, too. I will be starting this very same project this winter, from a 99 Z28 no less. I grabbed the factory 99 manuals off eBay for $50. My 99 is a T56 car, but I will be converting it to a (4L60E or 80) automatic (I will not waste the T56 – it will land in my 77 Z28). I still have to do the homework on the trans change, but I am currently leaning towards using a standalone trans harness.

A quick couple of question on your notes:
*Are you not having AC in your car (thus the deletes), or are you handling AC differently? I assume you are going no AC.
*What does TCS stand for? I cannot remember.
*Regarding the ballast resistor, when I talked to Mark at Mad Electric, we discussed this in regards to HEI conversions. For that swap, his opinion was to run the old coil ballast lead to trigger the relay, which in turn would feed full voltage to the coil. He felt that relay triggers require very little power to kick them. I’m just throwing that out there that maybe that is not a concern.
*What temp t-stat will you be running?
*Fans leads – hot at start – any concern on hot restarts the fans come on and draw juice from the starter?
*I see in the diagrams items like TCC ENABLE CIRCUIT. Are the basic harnesses the same for AOD and T56 cars?

Oh man, this is gonna be fun!

A quick couple of question on your notes:
*Are you not having AC in your car (thus the deletes), or are you handling AC differently? I assume you are going no AC.
*What does TCS stand for? I cannot remember.
*Regarding the ballast resistor, when I talked to Mark at Mad Electric, we discussed this in regards to HEI conversions. For that swap, his opinion was to run the old coil ballast lead to trigger the relay, which in turn would feed full voltage to the coil. He felt that relay triggers require very little power to kick them. I’m just throwing that out there that maybe that is not a concern.
*What temp t-stat will you be running?
*Fans leads – hot at start – any concern on hot restarts the fans come on and draw juice from the starter?
*I see in the diagrams items like TCC ENABLE CIRCUIT. Are the basic harnesses the same for AOD and T56 cars?

Oh man, this is gonna be fun!

The factory manuals are a lot of help for these swaps--I kept dragging mine back out to look up torque specs and assembly procedures.

- I don't have AC because I haven't bought an AC system yet. Thinking about a Vintage Air GenIV system. I'm going to try to integrate the compressor control with the computer when I do it.

- TCS is Tractional Control System

- My ballast wire was long-toasted. I ran a new wire and spliced it in near the ignition switch. I haven't tested what voltage it takes to throw a 30A Bosch relay, but I'd bet he's probably right--the ballast wire is probably sufficient.

- I'm still running the stock thermostat, 192F I believe. I dropped the fan temps to just above it so I don't have the fans beating on the thermostat. The general consensus seems to be that the LS1 should run at 180F-200F, and most people run a 160F thermostat and rely on the fans to keep it in the 180F-200F ideal operating range.

- No concern on the fan leads, the factory wiring had it going to BATT power instead of switched! The PCM still controls turning them on. I just don't like the idea of the PCM being able to decide on it's own to fire up the fans after I switch the key off. Stuff under the hood should stop moving when I turn the key off!

- The harness for 4L60E cars is different than for T56 cars. The engine part is the same, and the PCM is the same, but the trnas part is different. I think I've seen that it's possible to rework a T56 harness to work with a 4L60E. I'm not 100% sure if there are enough pins/wires you can move around on the PCM connectors to rig it. Someone like Speartech could definately rework it for you (they would have the connectors and pins). Or you could sell the manual harness and buy an auto harness. I'd definately stay with the main PCM control rather than a standalone box though--there's all kinds of cool integration between the engine and 4L60E control in the PCM.

I highly recommend buying your own tuning software so you can play with the PCM whenever you want, and most of the good software also functional as a realtime scan tool for troubleshooting. $500 worth of software+cable turns a $100 junkyard GM PCM into the equivalent of a $2000+ aftermarket EFI computer, with the reliablity of a factory part. (never been stranded by a GM PCM, but been stranded more than a couple of times by MSD ignition boxes and Electromotive controllers).

And yep, it will be a lot of fun. A few headaches to. There's no single right way to do most of it... there's dozens of different ways to do most of it, and ups and downs to each method. Fortunately there's a lot of people who've done this swap already. Now I saw a guy over on LS1Tech doing a DuraMax diesel swap into a 95 Z28--he's on his own!

Cool. I will be following your notes very intently. Thanks for the reply.

Hey, you keeping the cruise control? I plan to.

I'm planning on adding cruise control back to it one of these days--I need to buy cruise control module.