2020 Silverado Cab Penetrations for External Wiring

bzimmer82 · July 22, 2020

I have a 2020 Silverado Crew Cab that I am installing emergency lights on. I need to get a 4 awg and several 14 awg wires inside the cab from the exterior. I know there is a small grommet in the firewall that can be used, but they are not big enough for the group of wires I need to pull. What other options do I have to enter the cab? I see a silver ~3" metal plug under the rear seat on both the driver and passenger side, but they do not appear to be removable. Does anyone have any suggestions on how to get wires into the cab short of using a drill with a hole saw bit?

TrailBoss Owner · July 22, 2020

The hole used for the upfiter switches in the grommet for the main wiring harness through the firewall should be enough for any sort of aftermarket wiring needs. You can use relays external of the cab. If you don't know how to wire relays there are plenty of diagrams available and several aftermarket switch / relay kits that can be purchased that take care of the basics for you and the control wiring for 6 to 10 circuit kits will easily fit through the upfitter allowance in the grommet. Don't drill unnecessary holes in the truck. There other threads in this sight that will give you all the info and part numbers to get the gm upfitter switches if you dont like aftermarket. With todays technology of led lights I cannot imagine why you need a 4 gu. Inside the cab... but if you are still using halogen I would suggest a relay or constant duty solenoid as to not have to pull that gu of wire into the cab. Good luck!