Hello I have been gathering parts for a while and attempting my first swap. I have a 2001 Silverado 1500 4.3. The motor locked up on me. I got a l33 a year or so ago I plan on putting in. I have a wire harness that went to a 2001 6.0. I've seen you can repin the S,T,U pins on 4l60 plug to be a 4l80 and in the end you do don't use two wires. My question is if I wanted to do that in reverse are those 2 extra wires available on a 4l80 plug so I can convert it to plug into my 4l60? I was thinking I may just need to get another harness for a 2001 5.3 4l60.

 

4L80e to 4L60e: you will have to add the 2 wires
4L60e to 4L80e: remove 2 wires, move 1 wire. you will also need to ADD a twisted pair for the extra speed sensor

 

I still may go to the tuner I used before and take up his offer on one of those stand alone harnesses he sells with the correct plug we'll see. Thanks I appreciate the help

 

On my 99 4.3 to 5.3/4L80e swap, the repining at the case connector removed 2 wires that were then used for the second speed sensor (obviously also required a repining of the ECU connectors.) In other words, the existing wiring can all be used; no additional wires need to be to run back to the ECU.

It's pretty easy. LT1swap.com has the information.


Edit: but your V6 engine harness won't work on the V8 swap. You'll need a harness from a 99-02 V8. If you get a 99-02 2500 LS-based engine, then that's already ready for the 4L80e.