What does it take to change pcm's from a 411 to p59 with iac drivers. The vehicle is an 02 GMC Sierra. I have the green and blue connectors.

Are there any modifications that need to be done to the wiring?

Would like the option for growth with 3bar for Awd 2650 blower build.

 

I just converted a 2002 Silverado. There was a single alternator wire I read you have to move but it wasn’t in my harness so I didn’t have to do anything except swap the colored connector piece

 

I did my C5 a few weeks ago. Just moved pin 52/red to 75/green (same connector).

You will also need to disable a bunch of O2 sensor codes because the P59 has additional monitoring the P01 doesn't have. Or you can wire the sensor grounds to some previously-unused pins, but that's a lot of effort for not much benefit.