I have changed the transmission switch, checked the bulbs and fuse.
backup lights won't work on 1997 Plymouth Neon
Fuse #8 (10amp) in the fuse block? Check for 12V at the switch connector (white wire). Jump the white wire to the Violet / black wire and see if the lamps turn on. Also, squeeze the connectors with a pair of needle nose pliers to ensure a good contact at the switch.