Anubis
I'm Awesome
The stand alone harness I bought from lsx4u.com only needed like 6 wires connected to it from the old harness. I really don’t know what this guy was doing.
A good stand alone harness should include fuses for all the pink power wires (switched power) for ECM, injectors, o2 sensors, etc. and constant power to ECM. Have you located these fuses and checked for power there?
This is why I make my own harnesses. People pay for a plug and play solution but get cookie cutter junk. You can easily make your own with on line documentation. Stand alone harnesses do not always integrate well into a vehicles electrical system and compromises are often made that require weird wiring solutions to make them work..