v6 5 speed reverse lights not coming on
 

this was first noticed when i was getting an inspection sticker put on my car. Every other light works, just the reverse lights won't come on. I pulled the light out, bulbs are good, moved wiring around, sat back down in the bird, and the lights actually came on. i guess they worked for a while, but now i checked em off the reflection on my silverado, and they arent coming on. i was first thinking it was the switch on the trans because everytime i go to put it in reverse without completely stopping and putting it in 1st first, ya get a big CRRRRKKKKKKKKKKKK. what wires am i looking to inspect and where do they all go?

The backup light switch on the transmission has two wires - brown carries power when the ignition is on and light green goes from the switch to the backup lamps.