curtis73

This is an LQ9 with LS6 intake, AI 232cc heads and 234/240 cam going into an 86 El Camino with a T56. I have the factory ECM and wiring harness from the 04 Escalade donor, but its just the harness up to the firewall connectors - no cabin wiring.

Firstly, I have decided to pony up the dough for a wiring harness instead of hacking the original. Factory ECM does not have IAC driver, so I will be using an electronic TB. (need to get a pedal and box yet)

Second, when you folks do swaps like this, do you wire gauges directly from sensors or do you use the ECM outputs for sensors?

Most of my gauges are inoperable so I will be buying a gauge kit. Do the ECM outputs for gauges use typical GM sensor ranges, or do I need to buy special gauges?

There is an outside possibility that I may replace the entire dash with one from something like a GTO or Camaro depending on what is a close-ish fit. Will pretty much any 98-05 dash have compatible gauges?

Can you tell this is my first EFI swap?

G-Body

iTrader: (4)

Why not cut the 04 harness to fit? You already have most of what you need right there. The only inside wiring that you really need is between the TAC and throttle pedal, the gauge wiring, and the OBD II connector.

I use mostly factory gauges. Temp gauge needs the 86 sending unit cut down and rethreaded metric to go in the new engine. Oil pressure needs the 86 sending unit put in the new engine. Tachometer hooks up but you need to change the pulse per revolution in the PCM to put out a v8 signal. The speedo needs to be electric I usually hide the guts of a newer speedo behind the factory faceplate. Almost any dash with an electric speedo can be made to work, however, it will be easier to use a GM dash (rather than ford,chrysler, import) and try to make sure the dash does not need a BCM to function. I think you will lose some of the GTO dash functions without a BCM. The late 80`s to later 90`s GM clusters would probably be the easiest to swap in at least electrically.

curtis73

Its a possibility that I might hack the 04 harness, but until I buy pigtails for T56, extend the gauge harness, find a DLC, solder, crimp, shrink, curse, etc, it might be worth my money to buy one. Plug and play. Since this harness came off an 04 truck, and I have now installed an LS6 intake, using a T56 instead of the auto, and other changes, this harness might need to be so hacked that its worth getting a new one.

If it saves significant money, I might have some company re-do my harness since it only has 80k on it.

Normally, I'm the kind of guy who researches every single wire, what it does, the tech behind the signal, etc. I've built harnesses for old cars from scratch before, but the truth is, I'm getting old and I might just pull the trigger and buy this time.

I have the GM powertrain HPBooks manual that talks about LS engines and controls. Do you know of any tutorials or other publications that would give me an idea if its something I want to do on my own or hire out?

zTimbo

I've ordered a PSI harness and Speedhut Gauges for my swap. I've read good things about both of them. Will probably be adding to the many good reviews in the future.

33willys

iTrader: (1)

I got my harness from PSI because the truck harness was too short. Thing you have to watch out for is pedal/TAC/pigtail/tune compatibility.

curtis73

I would hope that whatever company I use would have access to that knowledge - I can say its a 6-pin TAC, a blue connector MAP, and a... just using examples.

G-Body

iTrader: (4)

Hmm. That is going to be interesting to find a harness for. There are not many vehicles that use a blue/green PCM, T56 and fly by wire. The caddy CTS V might be the closest factory harness as it does have a blue/green pcm, t56 and fly by wire but I`m not sure if the TAC and gas pedal are compatible with your pcm. Might be easiest to go with a a custom harness from one of the sponsors, or start hacking your truck harness.

compton-z28

i used an aftermarket harness from a company called Shwankee short blocks iam very happy with it. has been in my 72 camaro with ls6/t56 swap for over 5years with no problems

curtis73

No, no.... read again. I was just using random examples. I was making a hypothetical conversation between me and a wiring harness company. I was thinking that any of those companies worth their salt could make a harness for me if I tell them that I have a purple connector on the combobulator, and a lime green wire for the flux capacitor.

Its an 04 Escalade that donated the LQ9, PCM, and harness. I haven't even gotten that far in the build. All I know about the PCM is that it doesn't have the module for IAC, so I might as well use the drive-by-wire TB I already have.

nasty64

Good info for me as well. I'm using a 2007 5.3, dbw, th350, single turbo setup.... Doing alot of reading and I'm going to have a custom harness made for my car. Thx for starting a wiring/harness thread for us new guys