Conversions & Swaps LSX Engines in Non-LSX Vehicles
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Old Jan 13, 2012 | 09:24 AM
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Default Quick wiring summary

I've checked out some of the wiring diagrams and have been looking into ECM and harness kits.

I'm planning to swap in an LS1 into a 65 Chevelle. I have a fairly new wire harness in the car. Do the LS harness kits available account for everything such as gauges, tail lights, head lights, etc or are they specific for the engine management? I've been looking at the Pace Performance harness.

I'm confused on what I'll need. Do I need a harness for the LS engine, one for fuse box, gauges, lights, accessories, and an engine harness with ECM, an ECU, and etc?

The stock 65 Chevell harness has two plug connections on the firewall for the lights and for the engine harness. When I put a harness designed for an LS in the car, will I need to modify the firewall in some way for the connectors from the under dash harness to the engine harness connections?

From what I've read, it looks like I'll need a harness like the Painless Wiring LS FI kit, an ECM and engine harness, ECU and related wiring, and will still need something for gauges, accessories, and lights.
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Old Jan 13, 2012 | 09:43 AM
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If you go with PSI, or speartech they will make you a harness that control everything related to the engine. So the harness will run the engine, and also have connections for your gauges. Of course you will have to figure out some gauges like fuel, or wideband, depends on your application.

Yes, a separate harness will be needed for headlights, radio, blinkers, etc.
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Old Jan 13, 2012 | 10:17 AM
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I reworked the factory harness that comes with the pullout engine and am using the factory PCM. When I put mine in my 70 Chevelle, It will be a four wire hook up, only a hole in the firewall cuz I am mounting my PCM under the dash. I will Have battery pos and neg, crank and run wires to connect. I am using 700r4 so speedo is not and issue. There will also be a tach lead from the pcm to my aftermarket tach. I am using aftermarket mechanical guages that are already under the dash with the BBC. It took me about a week, working an hour here and there to finish my harness. I have the engine running on the stand. Hope this helps.
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Old Jan 13, 2012 | 01:32 PM
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As stated, our harness will include everything for the engine and transmission as well as extra wiring which will operate the tach, speedo, check engine light, fan controls, etc. The only integration with your existing chassis harness will be for switched/cranking power. Hope that helps. Questions let us know. Thanks.

Jon
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Old Jan 13, 2012 | 05:01 PM
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Thanks guys! Jon, I sent you a PM!

Dan
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Old Jan 14, 2012 | 08:55 AM
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Originally Posted by 99VetteFRC
I reworked the factory harness that comes with the pullout engine and am using the factory PCM. When I put mine in my 70 Chevelle, It will be a four wire hook up, only a hole in the firewall cuz I am mounting my PCM under the dash. I will Have battery pos and neg, crank and run wires to connect. I am using 700r4 so speedo is not and issue. There will also be a tach lead from the pcm to my aftermarket tach. I am using aftermarket mechanical guages that are already under the dash with the BBC. It took me about a week, working an hour here and there to finish my harness. I have the engine running on the stand. Hope this helps.
I did the same, but will be using electronic gauges.. but these wires are minimal. oil, temp, speedo. Fuel and alternator come from the rest of the vehicle wiring.

This was my 1st conversion, and it took me a week, an hour a day, to complete.

Sam
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