One reverse light out
 

I have a 2011 Sierra 1500 w/t. The passenger side reverse light is out and I can't seem to get it working. I'm hoping I am missing something simple. If it helps, at one time that particular light was full of water. The truck wasn't submerged, but that reverse light had filled up from rain/snow/condensation. If you have an idea, please let me know.

So far, I have
- replaced the reverse light bulb
- swapped in a different harness from the rear light distribution box to the passenger lights
- swapped in a new distribution box.

Again, any help is appreciated.

2011 Sierra 1500 W/T, 4.3 Auto, 230K miles

Have you checked the wires going to the light bulb socket to see if it is getting 12 volts and if there is a good ground?