rear wiper 03 tahoe

My rear wiper on 03 tahoe is erratic. comes on when switch is off. pulled fuse and still comes on occasionally. seems to come on when shifting to reverse or when turning on blinker?/??

I have had the same problem when I turn on the fog lamps. I was told there is a small surge from the lights to the wiper. It will jump off its purch and then go back. The cluster of switches are very close (fog lamps, head lamps, rear wiper). They have yet to correct the issue.