Chasing my tail, spent nearly an entire day on this without success. After lots of head scratching finally determined that one of the heavy red or red/white feed wires to the ignition switch never has power. Therefore, the famous GM yellow start wire never...

FIX posted 10/8/2021

iATN Members:
Login to view full TechHelp request
Auto Repair Pros:
Join iATN to read this TechHelp request
Vehicle Owners:
Find a nearby iATN member to repair your vehicle