I have a 2000 k2500 ive swapped to a 2004 lq4.
I used the 2004 wiring harness which was originally Blue/Green ECU and repined the connectors for the Red/Blue 0411 ECU.
Ive flashed in a 2001 Silverado k1500hd 6.0l Vin number into the 0411 ECU.
Problem is the oxygen sensors always read 440-450mv. Ive checked all the wiring and everything is good and pinned correctly and I do not have after cat o2 sensors or the wiring to them. They are new AC Delco sensors. Ive looked at the pinout for the 02 camaro and it does not show O2 heater grounds going to the ecu but the 01 silverado does. I thought they were the same ecu. Do I need to pull the heater grounds and ground them to the block instead of them going to the ECU?

 

You're right that the 0411 o2 heaters don't ground to the pcm. If you have them wired to ground to the pcm they likely aren't heating..since your pickup has changed. Ground them to the chassis or engine.
See https://ls1tech.com/forums/conversio...g-diagram.html

 

I wonder if thats the reason I never get them to read anything other than 450mv as they are not heating up and they are at the collectors of open headers. I have a muffler on order. I have the 04 pcm which is the green/blue 12586243. I wonder if it would be better to switch to that one instead of using the 0411.