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Discussion Starter #1
I'm in the process of converting my automatic 1998 Chevy K2500 to 6BT/NV4500.

I've read that the reverse switch is located on the column on the GMT400s. I've removed all the componentry associated with the automatic shifter and now I'm trying identify which wires to reroute to the reverse switch on the NV4500.
 

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On my 96 the park/neutral switch on the side of the transmission turned the backup lights on. By connecting the pink and light green wires to the nv4500 switch they work perfectly.
It could be different on your 3/4 ton but I bet it's similar.
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Discussion Starter #3
On my 96 the park/neutral switch on the side of the transmission turned the backup lights on. By connecting the pink and light green wires to the nv4500 switch they work perfectly.
It could be different on your 3/4 ton but I bet it's similar.
Okay it looks like I’ve really screwed up then. I removed all transmission related wiring from the powertrain harness and re-loomed most of it. Where do those pink and lt green wires go from the neutral switch? I assume I can just re-wire to the NV4500 from wherever I cut or unplugged them within the remaining harness.

I really appreciate the assistance.
 

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The pink wire is key on power from the engine harness and I "think" the light green went through one of the connectors on the firewall below the brake booster on back to the lights but I will check in the morning.
 

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Discussion Starter #5 (Edited)
So based on this pin out chart from GMT400.com I’ve located where light green the backup lamp wire goes to from the original neutral safety switch. Position D3 on the firewall connector. You can see in the photo of my connector that I have two pink wires (positions A2 and C7) that are cut from the old trans harness and I assume one was the pink wire that completed the circuit for the reverse light switch on the 4L80E. Can someone confirm which of these are the correct wires to run to the NV4500 reverse light switch?

Or did the pink wire for 4l80e reserve light switch originate from somewhere else?

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Discussion Starter #6
I got it sorted.

With an unmolested harness, Yoder is totally accurate about taking pin F (light green) and pin C (pink) from the existing C2 plug on the neutral safety switch of the 4l80E harness and connecting them to the reverse light switch plug on the NV4500.

I screwed up and cut the whole 4l80e harness out prematurely 🤦🏻‍♂️. The light green wire from the NSS makes a “Y” and one side goes to the junction box on the driver side firewall and the other side goes to the taillights. The pink wire from the NSS goes straight to the same junction box on the firewall. I ended up going the junk yard to examine a harness and replaced everything I had hastily cut out.
 
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