lt1 standalone wire harness

I am now in the market for a standalone wire harness. What did you guys do. I am not using my stock harness its to old and brittle. I was looking into the techrods or fuelinjectionconnection for harnesses. Or does someone have a spare standalone wireharness out there. I have the ecu/pcm reprogrammed already by pcmforless.

I went through speartech for my LS1 harness. His site is dedicated to the chevy and GM motor harnesses.

I have one that is almost finished and I do an exchange deal. PM for a price.

I used some of my christmas money and got a PSIConversion harness. I will let you guys know how it looks and works. I have a question on the harness that comes out of the firewall. There is a set of 3 wires. One is red and blue and the other 2 are a solid red with eye loops and a couple of 2 pin plugs. What are they for? Did they go to the battery or what not and some sensors. Its been a while since i took the 944 harness off. I am getting very close to getting all the parts for the conversion. I just need the headers/motor uprights/motor mounts/msd opti/vss gear and bracket, and a couple of little odds and ends. Does anyone one have a set of headers or uprights and motor mounts laying around.

This is what i have so far
c5 one piece bellhousing machined pockets for the Tickperformance bleader etc.
new flywheel
new 10.5 clutch disk
new 10.5 pressure plate
self machined bellhousing adapter plate
self machined pilot bearing adapter and bearing
self machined Brake booster delete plate and push rod
c5 throw out bearing and the needed 3an hoses
new FAG clutch mastercylinder
Psi conversion standalone wire harness

So far so good. Slowlly but surelly. I wouldnt have even thought about doing this swap with out all the info and technical information from you guys. I thank you. I cant wait to get this thing fired up and driving.

There is this website that I know of that sells everything you need, I be leave it's called [You must be registered and logged in to see this link.]

i will be hitting them up really soon for the uprights and vss gear. I wish they had a modded oil pan for sale for the lt1.

Does anyone know what the 3 wires at the end of the harness on the firewall are. I still cant seem to find out where they go. 2 are solid red and the other is red and blue. Did they go to the starter or straight to the battery.

I can get the LT1 pan for you, I just haven't had one to get a picture for the website.
Post a picture of the wires, sometimes that will help get an answer, The wires don't ring a bell with me.

Does anyone know what the 3 wires at the end of the harness on the firewall are. I still cant seem to find out where they go. 2 are solid red and the other is red and blue. Did they go to the starter or straight to the battery.

If memory serves....two red (4mm thick) wires went directly from the battery to the fuse panel as 12V+ feed and a red/blue (4mm thick) wire, as well, direct from the battery to "terminal 2" of the fuel pump relay.

I have to ask, (since there’s no picture ) is your fuse panel still installed in the car as in stock form? I’m trying to figure how these three wires (if they are what I’m assuming they are as above) have come to be detached from whence they came????

Pictures here are very important and helpful. But, hope this helps!

that sounds accurate. I still do have the original fuse panel in the car. I only took out the DME. I would like to use the original fuel pump wires instaed of routing new ones. How would i go about doing that. The harnes i have has afuel pump load wire i have to add to the block. Where is the fuel pump load wire so i can splice into it.

yes you are right. The 2 red supply the fuse panel and the red and blue supple the fuel pump relay. Does that mean i will not be using the red and blue wire at all. If i give the standalone harness fuse block a constant 12v and an ingintion 12v the brown wire will turn the pump on/off. The other wire off the pump must be a ground wire to chassis. Does that sound rite.

that sounds accurate. I still do have the original fuse panel in the car. I only took out the DME. I would like to use the original fuel pump wires instaed of routing new ones. How would i go about doing that. The harnes i have has afuel pump load wire i have to add to the block. Where is the fuel pump load wire so i can splice into it.

Should be pin 9 of the fuel pump relay. The wire is black/green (1.0mm thick) I believe. You should have to take the fuse block out and find this wire and splice into it.

yes you are right. The 2 red supply the fuse panel and the red and blue supply the fuel pump relay. Does that mean i will not be using the red and blue wire at all. If i give the standalone harness fuse block a constant 12v and an ingintion 12v the brown wire will turn the pump on/off. The other wire off the pump must be a ground wire to chassis. Does that sound rite.

Heres a highly simplified schematic.
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So how much $$$ do you have in your conversion thus far, if you don't mind me asking? I'm tinkering
with the idea, but I'm not ready to commit.

Sounds like you did a lot of the fab work yourself, did you get a copy of the "Conversion Manual"?

Thanks for the info

Too much money and too much work. But concidering I am a cnc machinist not a mechanic it is possible with the right tools and enough money anyone can do anything. I have problly spent 4500$ - 5K including the car, and the engine is still on the engine stand.

I got all my info from this website. I have not fitted the engine into the car yet but i am sure it will bolt up i am hoping.
The kit from texas performance would be the best bet for someone who doesnt have machining experience

I have the oil pan texas customs made on the engine which fit perfectlly not a one person job i might say with a new gm gasket.
the sanderson headers are on with the permatex never seen that before,
the msd is bolted in,
the new water pump is bolted on,
motor mounts are on,
Rebuilding the throttlebody today,
Going to have to get the intake cleaned out somehow too much cabon build up, Any one clean then themselves

Foaming oven cleaner will do amazing things to your intake, just be careful it'll also take off paint!

What do i do with the coolant going through the throttlebody. How do i go about deleting this option. I see the pipe that goes from the head to the throttlebody i am just not sure where to loop that line. If anyone has anypics that would be awesome. The throttle body is untrasonicd cleaned and now I will be tackeling the intake. I am just confused about the whole coolant through the TB

shwinny wrote:What do i do with the coolant going through the throttlebody. How do i go about deleting this option. I see the pipe that goes from the head to the throttlebody i am just not sure where to loop that line. If anyone has anypics that would be awesome. The throttle body is untrasonicd cleaned and now I will be tackeling the intake. I am just confused about the whole coolant through the TB

Just bypass it back to the radiator.

Suggest that you go to the Griffin web site and read the article on plumbing the LS1.
There is a great diagram that indicates where to connect the steam pipes.

fliermike45 wrote:Suggest that you go to the Griffin web site and read the article on plumbing the LS1.
There is a great diagram that indicates where to connect the steam pipes.

LS? I think he's putting an LT into his car.

Sorry. Sometimes it just runs together on me.

Simply disconnect the hose from the throttle body and on the passengers side of the intake is the head steam vent tube....Connect it to that. Pretty simple.
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I actually took the passage cover to the bandsaw and cut if totally off the ThrottleBody, so its just the Idle control cover no Coolant passage. My intake is at the engine builder getting a Spa Day/ bead blasted. Getting ready for a suit of FORD Blue.

I actually went to Mcmaster carr and bought some 90 Degree fittings and some blue 3/8 high temp silicone tubing to bolt to the back of the LT1 Heads. Not sure where to dump it? maybe back into the radiator or reservior The parts were only 30$ compared to 100$+ For a crossover tube from GM

dyslexic