Looking at the blinker wiring diagram it looks like the flasher module could be causing the issue as well. Here is its location (below)
I would check the rear junction block for damage moisture.
"Rear Lamps Junction Block On rear inner side of right frame rail."
Please let us know what happens.
Cheers, Ken
Images (Click to make bigger)
Tuesday, November 7th, 2017 AT 11:30 AM