Where is the backup light switch on a 1999 Chevy S10 pickup with manual transmission?

The 1999 Chevy S10 pickup, with a manual transmission, doesn't have a separate backup light switch. The backup lights are activated by a switch built into the transmission itself. There's no separate switch to adjust or replace on the dash or elsewhere. If your backup lights aren't working, the problem lies within the transmission switch, wiring, or the lights themselves.