Back up light problem

I have a 2002 Chevy Express 3500 van. Whenever I put this vehicle in reverse, the 20amp fuse that serves both the directional signals and the back up lights burns out. With a new fuse, the directionals work fine. But once I put this vehicle in reverse, the fuse burns out again. I have replaced the light bulbs in the back up lights with no change in this all of a sudden recurring problem. Has anyone dealt with this problem before and fixed the problem. Thank you for any help with this problem.

Sounds like a frayed wire going to the BU lights. Shorting out when energized.