During installation of new battery in my 2018 GMC Sierra 1500 SLE 5.3 Z71 the battery cables were crossed and hooked up backwards. Realizing what was done, connected everything correctly and now engine light and battery lights are on inside on the dash along with service battery charging system notification and radio completely off and unavailable, blinkers not working, and power locks not working.
So after replacing with new battery, truck started no problem but after running for 30/45min, it died and needed jump box to start. After using simple box to start it died soon as cables were disconnected. After doing that few times it wouldn't start at all. Tried using another vehicle for jump and would not start even with the battery reading around 14 on the gage on dash. Got to the point were there wasn't anything happening when tuning the key, nothing at all, completely dead.
Tried replacing alternator but truck wouldn't start on its own after installation, had to jump start it and after disconnection of cables, the truck slowly loses power and dies out. (Come to find out the original alternator wasn't bad) New battery, new alternator, truck not starting, service engine and service battery lights on inside on dash along with the same service notifications cycling through the information panel in dash. Also radio, blinkers, and power locks not working
service engine and service battery lights on inside on dash
you need to run a full diagnostic with a good tool to find out why the lights are on
During installation of new battery in my 2018 GMC Sierra 1500 SLE 5.3 Z71 the battery cables were crossed and hooked up backwards.
It's quite possible you fried computer modules, they don't take kindly to reverse polarity voltage being applied and it only takes a fraction of a second for destruction to occur. You could check to see if any fusible links or master fuses have blown out.
