6.2 to 350 swap

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custodian

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William
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5.3 LS, 350
Both glow plug wires? There are 8, green wires. Or did you cut off at the start of where they branch off to 4 on each side and use those? I did not know they were constant ignition power? I want to keep wires intact in case I go back to the diesel.
Cut the eight off and start from there, you'll end up with two. Yes, voltage when key is turned on. I used one for the electronic distributor.
 

Wallace6

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Ray
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I have what looks to a harness coming out of the fuse box. No cuts I can see. I will never go back to diesel in this rig. I know how hard it is to find these pieces when needed lol
 

RamblinGMC

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c2500
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6.2
Cut the eight off and start from there, you'll end up with two. Yes, voltage when key is turned on. I used one for the electronic distributor.
Thanks! I guess I will cut them where they branch off and just save the ends in case I ever go back.
 

Buck69

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Sorry for chiming in late. My rig is a CUCV, so lots of differences in the harnesses (including 2nd alternator for 24v), but believe the 6.2 stuff is the same. I'm not quite to the same stage as you yet but will be in the next couple days.
The power to the green glow plug wires are switched on and off with a relay controlled by the glow plug module which is engine temp sensitive. They are of no use to you for ignition power.
I removed all the 24v and diesel stuff. I know there is switched ignition power to the injection pump on the 6.2 for fuel shut off. Not sure what else is there yet but will be figuring it out in the next couple days. Am also looking for keyed power for the alternator excitation. Just haven't got there yet.
Hopefully someone else chimes in in meantime if you are in a hurry.
 

RamblinGMC

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c2500
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6.2
Sorry for chiming in late. My rig is a CUCV, so lots of differences in the harnesses (including 2nd alternator for 24v), but believe the 6.2 stuff is the same. I'm not quite to the same stage as you yet but will be in the next couple days.
The power to the green glow plug wires are switched on and off with a relay controlled by the glow plug module which is engine temp sensitive. They are of no use to you for ignition power.
I removed all the 24v and diesel stuff. I know there is switched ignition power to the injection pump on the 6.2 for fuel shut off. Not sure what else is there yet but will be figuring it out in the next couple days. Am also looking for keyed power for the alternator excitation. Just haven't got there yet.
Hopefully someone else chimes in in meantime if you are in a hurry.
Well if you get there, let me know what you figure out. I most likely won't get that far this weekend. Still have a few little things to get done with the new engine. Thanks for the help!
 

Buck69

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Well if you get there, let me know what you figure out. I most likely won't get that far this weekend. Still have a few little things to get done with the new engine. Thanks for the help!
So, had time to look a bit further today on my CUCV for you. I just want to remind you again, our harnesses and fuse blocks are not the same but I would suspect the 6.2 related stuff is. Do your own due diligence.
The fuel shut off on mine is a 10 ga pink wire. It is controlled straight from the key switch. Powered in the start and run positions. It has no fuse at the fuse block and is only protected with the fusible link on the firewall for the entire ignition circuit. You may want to add something to protect whatever you use it for.
There is also a white wire on mine for a fuel heating element on the fuel filter housing. It is powered during the accessary and run positions. It T's into the power for the wiper motor and is protected in my fuse panel with a 20A fuse. Thinking it is for wiper home.
The only other power left in my harness is a 14 ga red wire that is battery power from the the firewall isolator which was used in the 2 pin plug (with a brown) on the 12v alternator. It is live all the time and is only protected with a fusible link.
There is a another pink/black wire at the fuel filter housing (for the water in fuel sensor) which has power in the run position. Do not use this one. It is sensor power from the gauge cluster and likely will not take any kind of a load.
I have completely removed all the diesel and 24v stuff including harnesses, module and relays. I have a few spare wires now on both sides of the firewall for use down the road.
Good luck!
 

RamblinGMC

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Clovis Ca
First Name
Eddie
Truck Year
1982
Truck Model
c2500
Engine Size
6.2
So, had time to look a bit further today on my CUCV for you. I just want to remind you again, our harnesses and fuse blocks are not the same but I would suspect the 6.2 related stuff is. Do your own due diligence.
The fuel shut off on mine is a 10 ga pink wire. It is controlled straight from the key switch. Powered in the start and run positions. It has no fuse at the fuse block and is only protected with the fusible link on the firewall for the entire ignition circuit. You may want to add something to protect whatever you use it for.
There is also a white wire on mine for a fuel heating element on the fuel filter housing. It is powered during the accessary and run positions. It T's into the power for the wiper motor and is protected in my fuse panel with a 20A fuse. Thinking it is for wiper home.
The only other power left in my harness is a 14 ga red wire that is battery power from the the firewall isolator which was used in the 2 pin plug (with a brown) on the 12v alternator. It is live all the time and is only protected with a fusible link.
There is a another pink/black wire at the fuel filter housing (for the water in fuel sensor) which has power in the run position. Do not use this one. It is sensor power from the gauge cluster and likely will not take any kind of a load.
I have completely removed all the diesel and 24v stuff including harnesses, module and relays. I have a few spare wires now on both sides of the firewall for use down the road.
Good luck!
Thanks for the info! I will look at mine and see what I can figure out.
 

RamblinGMC

Member
Joined
Aug 21, 2022
Posts
43
Reaction score
40
Location
Clovis Ca
First Name
Eddie
Truck Year
1982
Truck Model
c2500
Engine Size
6.2
So, had time to look a bit further today on my CUCV for you. I just want to remind you again, our harnesses and fuse blocks are not the same but I would suspect the 6.2 related stuff is. Do your own due diligence.
The fuel shut off on mine is a 10 ga pink wire. It is controlled straight from the key switch. Powered in the start and run positions. It has no fuse at the fuse block and is only protected with the fusible link on the firewall for the entire ignition circuit. You may want to add something to protect whatever you use it for.
There is also a white wire on mine for a fuel heating element on the fuel filter housing. It is powered during the accessary and run positions. It T's into the power for the wiper motor and is protected in my fuse panel with a 20A fuse. Thinking it is for wiper home.
The only other power left in my harness is a 14 ga red wire that is battery power from the the firewall isolator which was used in the 2 pin plug (with a brown) on the 12v alternator. It is live all the time and is only protected with a fusible link.
There is a another pink/black wire at the fuel filter housing (for the water in fuel sensor) which has power in the run position. Do not use this one. It is sensor power from the gauge cluster and likely will not take any kind of a load.
I have completely removed all the diesel and 24v stuff including harnesses, module and relays. I have a few spare wires now on both sides of the firewall for use down the road.
Good luck!
Got it all figured out and she purrs like a kitten! Just need to replace tanks now and she will be on the road! Thanks for the help!
 

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