Started the GM upfitter switch install. Not in a big hurry (don’t have anything to connect to them) so don’t know when I’ll do part 2 but I have all the under dash connections done (minus 1). Looking at the underhood items and location of grommet on the firewall seems like getting that pushed through there is gonna be a pain in the rear.
My truck was optioned with the upfitter switches. The switches were pre-installed under the center stack in the dash from factory. Everything else; fuse/relay box, wiring harnesses, and battery terminals/connections came in a couple bags under the rear seat to be installed by owner. Thanks GM. That’s what a $150 option I believe gets you.
Have to remove 2 lower dash pieces and the two “woodgrain” trim pieces on both sides of console. This allows you to make connections to the back of the switches/buttons, the trucks main wire harness and attach the fuse/relay box behind the lower dash. One more connection will need to be made once the battery power wire is ran through the firewall. Also, mine did not come with 2 screws to attach the fuse/relay box to the lower dash. They are part # 11589015. This is the upfitter bulletin I’m using, install procedure 2 for my trim level.
Apologies for the lack of pictures