DIY LSx Stand Alone Harness Myths

Tech by Tim Stockwell
Publisher’s Note:  Tim Stockwell is at it again with an introductory piece on what you’ll need to consider if you want to swap an LS engine into, well, anything.  Read the intro story, watch the video, and comment here if you have any questions for Tim.  Good stuff from Cars Illustrated …
After obtaining a 2000 Camaro Z28 driveline complete with original harness and computer, I started calculating costs involved in swapping it into something. I kept ending up allowing a good portion of the budget to either a new stand alone harness or paying for one of the many people out there advertising to convert your existing harness to stand alone. As a Commercial/Industrial Electrician by trade, I just couldn’t seem to do that since I already had what GM had designed to run this motor.
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After a few days of digging through the internet, I gathered enough info, I thought, to attempt this magical mystery project myself. I found detailed pin out charts telling you where every wire out of the PCM went, and made sure I knew what each and every sensor or electronic gadget on the motor was.
After spending two hours getting the wire loom and tape off of the original harness (!!!) I laid it out on the motor itself, and started with my pin out chart eliminating anything that would no longer be used while keeping what I needed. That process went quickly, with about a half an hour of labeling, checking,  and double checking, then snipping and pulling it back to the PCM and taping off the ends just in case I made a mistake and need it later.
What this ended up all coming down to is so simple anyone can do this, and everyone should try before paying someone else to do it.  Eliminate things you aren’t going to use, then all you have to do is make sure all orange wires go to a constant +12v source, all pink wires go to a key on +12v source, and all the black wire go to a good ground.  Your starter solenoid wire is existing in whatever it is that you are putting your LSx into from your existing ignition switch, and the starter needs a constant +12v from at least a #10 wire and a 20/30a circuit by itself. A good idea is to break down and fuse things like injectors, PCM power, and coil pack power, but for our experiment we just wired it all to our test battery as it was temporary anyways.
It’s as simple as doing this, hooking up 3 wires, and Vroooom! You can also use the stock harness to easily trigger relays for fuel pumps, electric fans, check engine light, or anything that a 2000 Camaro had as far as engine controls. I also ended up getting a dash cluster and pigtail and took it a bit further. I hooked up another of the six wires to have the cluster function showing engine temp, oil pressure, battery voltage, tach, check engine light, and so on.
Moral of the story, if you can wire up an outlet in your house, you can make your own stand alone harness.  It’s that easy.
 I found it easier to visualize with the harness actually on a motor, seem to make everything easier and there was no question where anything went or what it did. Don’t be intimidated by all of this.  our pin out will tell you every wire color and it’s position in the PCM connectors.
Video of it running-
In true Cars Illustrated fashion, our motor was started on a regular engine stand, but with a chain and engine hoist to keep it from rolling over, and a fire extinguisher just in case.  I’ve been known to have more than one project up in flames, but we won’t talk about that. We rigged up a kick ass fuel system by dropping an electric pump in a jug of gas, feeding a Corvette filter with built in regulator and return port back to the jug, and the outlet side right to the fuel rail. This thing literally fired on the first hit, and ran like it was still in the car.  If you can bolt an LSx motor in, you can get it running yourself.  There is no magical process….no wizardry involved…….put that money into something more useful…like beer and steaks for the grill..

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