95 wiring removal

Hello, I am in the process of removing all of the now unused wiring from my original harness, 95 chevy originally 350tbi, now it's a 6.0 LQ4 with my original 4L60E trans. My question is does anyone know exactly which wires can be removed, BTW I am buying a harness from nelson as soon as I can afford it. For instance I have already removed all of the wiring that went to my original computer from the harness, which comprised most of the harness, but there were 3 plugs at that end of the harness, 2 for computer and 1 that plugs in the dash harness, will I be able to hook up to the dash harness directly or not. I have searched and found a lot but not everything I need to know yet. Any help is appreciated. Thanks

so you took all the wiring out of the engine bay?
you didnt keep your AC/water temp/ALT wire/Oil Pressure sensors?
thats all i kept outta my harness. im about to hook up the speedo wire as soon as i find the post by Redheartbeat then ill be ready to roll once my tune is done :)

Yeah I kept those, as well as the original vss wire, but it's all the other's. Especially the third plug inside the cab that I mentioned.

why did you keep the VVS, the NP harness will control the engine/tranny :)
all you need is a 12v, IGN, FP, Ground with that harness other than your sensors :)

I only removed the wires that I knew what they were. I dont know how much different yours is than mine but as far as the plugs in the dash I just unplugged the ecm, removed it, and left the plugs alone. I cut out 20 or so wires at the firewall. Looking at diagrams, i was suprised how much wiring was needed left alone. For instance, much of the wiring on the junction block on the firewall is still needed for grounds and powers for the body wiring. Also, the fuel pump relay is located next to the junction block which I used in my conversion. Im sure there are wires left that could be removed (unused wires inside the dash, for instance) but I think it would almost take removal of the dash to completely remove all unneeded wires. I recommend getting some wiring diagrams for the engine compartment, passenger compartment, and ecu and only remove what you know. Dont simply take what you need and cut everything else. If you do, you will end up with a bunch of stuff pertaining to the body harness that doesnt work.

Yeah, I will remove the vss wires, I don't know why I was thinking I needed them, and I believe I have most of the rest of it figured out, but we shall see.

On my '96, I bought the GM Service Manual that had all the trucks wiring in it. Easy to understand & tells you the purpose of every wire that comes out of the firewall and the entire truck. Invaluable.

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Originally Posted by LS1GMCTruck

On my '96, I bought the GM Service Manual that had all the trucks wiring in it. Easy to understand & tells you the purpose of every wire that comes out of the firewall and the entire truck. Invaluable.

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Sounds cool. Im a real wiring dummy and I need one that gives the physical location of each wire and/or solenoid lol. Or, even better, one that says "this color wire located here is likely this" lol.

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Originally Posted by flattopwill

Sounds cool. Im a real wiring dummy and I need one that gives the physical location of each wire and/or solenoid lol. Or, even better, one that says "this color wire located here is likely this" lol.

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So "was" I. Never thought I would understand any of it. But, now I know(basically) how a LS1 computer functions, so I understand what to do. Yes, the book tells you where & what each wire does.

Where did you purchase the GM Service Manual and cost?

Look here:
Helm Incorporated: Choose Product Category

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Originally Posted by keniff

why did you keep the VVS, the NP harness will control the engine/tranny :)
all you need is a 12v, IGN, FP, Ground with that harness other than your sensors :)

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Doesn't the speedometer also require the VSS?

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Originally Posted by gl18rider

Doesn't the speedometer also require the VSS?

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The new harness will have a vss that goes from the trans to the pcm. The pcm has a speedo output that runs to the old speedometer.
I, on the other hand, spliced into the new vss and connected the old vss to make my speedo work. The way I did it is not how I recommend it and I will probably change it in the future. If you use the speedo output from the pcm then it is tunable for gear changes, tire sizes etc.