How to remove the factory truck wiring? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jrblanke · 07-20-2017, 02:07 PM

Hey guys,

I was hesitant to post this, because perhaps I just need to spend some more time looking at the wiring diagrams while sitting in the engine compartment. But I’ll go ahead and post to get your thoughts.
I have a few questions about removing the factory chevy wiring. Specifically the method by which you removed your old wiring. My truck is a 1984 2wd model, and it will be getting a 2006 5.3/4L60 with a BP automotive standalone harness (which I already have).

Here are my questions:
1. Does anyone have a list of wires that can be eliminated?
2. When removing the wires, did you cut them at the firewall connector, or can they be removed completely from the connector?
3. How do I physically remove them from the truck without causing a problem? (I'm thinking about shorts, and damaging the connector).
4. Did anyone install the motor and get it hooked up first, before e4iminating wires?

I am using the wiring diagrams from 73-87chevytrucks.com.

My fear is cutting something that I will need later, or cutting the wrong wire and then having to chase down something not working.

The headlights and front end harness was easy to isolate. Also the power wires, starter, and alternator were easy to find and isolate as well. The other wires for sensors, gauges, air conditioning and transmission were a little tougher for me to discern.

Like I said in the beginning, perhaps I just need to spend some more time with the wiring (new and old) to get a better understanding of what goes where and does what.

**dec010974** · 07-20-2017, 06:16 PM

hello jrblanke. Hold up. Before you start slicing and dicing, there are three main sources you need to identify first. I am not a professional installer but I have done a few LSx swaps. If it were me, I wouldn't remove anything. I would tap into my sources and keep it moving. The most important sources are +12 volt battery, +12 volt Ignition, and (-) ground. The LSx, BP harness needs these sources to run your eingine. Once you have located these sources, I would figure out how you are going to lay out your wiring. There is a junction block that ties the starter, alternator, and inside fuse panel to the +12 volt source of the battery. This is just my suggestion. If i am correct, 1982 chevy c10 has minimal wires. It should be simple, bt i have done this many times. On most of my swaps, the 30-40 year old wiring just didn't cut it for me and I rewired the whole vehicle with a truck fuse panel harness. PM me your number and ill try to help you out. Good luck and have fun with your swap.

**mongocanfly** · 07-20-2017, 08:43 PM

You really don't need to remove any of the trucks wiring...all the trucks power goes thru the 2 post block on the firewall..
All the LS needs is switch on power...constant power...and grounds..
I used the big wire going to the hei for my switch on power..
I hooked to the firewall block for my constant power...
Grounds are self explanatory...the more the better..
The same wires that fired your old starter will work on the LS starter..
The alternator wire hooks right to the post..
If you have electric gauge senders they all hook back up with the proper adapters..although you may have to move the water temp sender for the gauges to the passenger side head..
Only thing you might want to remove would be the hei plug...

jrblanke · 07-21-2017, 08:30 AM

Thanks guys. I felt dumb posting my questionsyesterday, but I did it anyway.

Its been about 10 months since I worked on the project, and am just getting back into it (I have a daughter due next month and am going to try to get as much done before she comes).

I haven't cut anything yet. I guess I was just thinking, since the harness is stand alone, I should be able to get rid of wires that were part of the old engine and transmission (besides the 4 main wires mongocanfly mentioned and the oil/water temp sending units).

I like the suggestion of just getting everything in and running, then see what's left over that can be removed. It will be a learn as I go kind of thing.

**mongocanfly** · 07-21-2017, 02:47 PM

Yep ..that would be best...drop in engine and wire it up...there's very little interface between the truck harness and the engine harness..

07-20-2017, 02:07 PM	#1
jrblanke Registered User Join Date: May 2011 Location: Raleigh, NC Posts: 240	How to remove the factory truck wiring? Hey guys, I was hesitant to post this, because perhaps I just need to spend some more time looking at the wiring diagrams while sitting in the engine compartment. But I’ll go ahead and post to get your thoughts. I have a few questions about removing the factory chevy wiring. Specifically the method by which you removed your old wiring. My truck is a 1984 2wd model, and it will be getting a 2006 5.3/4L60 with a BP automotive standalone harness (which I already have). Here are my questions: 1. Does anyone have a list of wires that can be eliminated? 2. When removing the wires, did you cut them at the firewall connector, or can they be removed completely from the connector? 3. How do I physically remove them from the truck without causing a problem? (I'm thinking about shorts, and damaging the connector). 4. Did anyone install the motor and get it hooked up first, before e4iminating wires? I am using the wiring diagrams from 73-87chevytrucks.com. My fear is cutting something that I will need later, or cutting the wrong wire and then having to chase down something not working. The headlights and front end harness was easy to isolate. Also the power wires, starter, and alternator were easy to find and isolate as well. The other wires for sensors, gauges, air conditioning and transmission were a little tougher for me to discern. Like I said in the beginning, perhaps I just need to spend some more time with the wiring (new and old) to get a better understanding of what goes where and does what.

07-20-2017, 06:16 PM	#2
dec010974 Senior Member Join Date: Oct 2012 Location: Miami, Florida Posts: 932	Re: How to remove the factory truck wiring? hello jrblanke. Hold up. Before you start slicing and dicing, there are three main sources you need to identify first. I am not a professional installer but I have done a few LSx swaps. If it were me, I wouldn't remove anything. I would tap into my sources and keep it moving. The most important sources are +12 volt battery, +12 volt Ignition, and (-) ground. The LSx, BP harness needs these sources to run your eingine. Once you have located these sources, I would figure out how you are going to lay out your wiring. There is a junction block that ties the starter, alternator, and inside fuse panel to the +12 volt source of the battery. This is just my suggestion. If i am correct, 1982 chevy c10 has minimal wires. It should be simple, bt i have done this many times. On most of my swaps, the 30-40 year old wiring just didn't cut it for me and I rewired the whole vehicle with a truck fuse panel harness. PM me your number and ill try to help you out. Good luck and have fun with your swap.

07-20-2017, 08:43 PM	#3
mongocanfly Post Whore Join Date: May 2015 Location: Alabama Posts: 14,662	Re: How to remove the factory truck wiring? You really don't need to remove any of the trucks wiring...all the trucks power goes thru the 2 post block on the firewall.. All the LS needs is switch on power...constant power...and grounds.. I used the big wire going to the hei for my switch on power.. I hooked to the firewall block for my constant power... Grounds are self explanatory...the more the better.. The same wires that fired your old starter will work on the LS starter.. The alternator wire hooks right to the post.. If you have electric gauge senders they all hook back up with the proper adapters..although you may have to move the water temp sender for the gauges to the passenger side head.. Only thing you might want to remove would be the hei plug... Last edited by mongocanfly; 07-20-2017 at 09:09 PM.

07-21-2017, 08:30 AM	#4
jrblanke Registered User Join Date: May 2011 Location: Raleigh, NC Posts: 240	Re: How to remove the factory truck wiring? Thanks guys. I felt dumb posting my questionsyesterday, but I did it anyway. Its been about 10 months since I worked on the project, and am just getting back into it (I have a daughter due next month and am going to try to get as much done before she comes). I haven't cut anything yet. I guess I was just thinking, since the harness is stand alone, I should be able to get rid of wires that were part of the old engine and transmission (besides the 4 main wires mongocanfly mentioned and the oil/water temp sending units). I like the suggestion of just getting everything in and running, then see what's left over that can be removed. It will be a learn as I go kind of thing.

07-21-2017, 02:47 PM	#5
mongocanfly Post Whore Join Date: May 2015 Location: Alabama Posts: 14,662	Re: How to remove the factory truck wiring? Yep ..that would be best...drop in engine and wire it up...there's very little interface between the truck harness and the engine harness..



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