Hi my name isXXXXX to just answer.
When the fuse blows , Yes it means that there is a short to ground in the circuit for the turn signals , if that is the fuse that is blowing. Bulbs will not cause a short, that will blow the fuse.
You need to inspect the wiring from the turn signal switch back to the rear lamps.
Look for areas that have a rub mark on them. Any where it makes a sharp turn, like where the harness passes down the left frame rail near the back of the left inner fender,.
The harness can cut itself on the inner fender and cause a short. Also if there is a trailer plug. Check this wiring carefully, even inside the plug where the wires connect.
Any bare spot can short to ground. The wire colors of the wires you want to check will be yellow( left turn) and dark green (Right turn).
If you need more information on this concern Please Ask.
I haven't forgot about you I just havent been able to work on my truck. I will this weekend.
One quesition though, what is the color of the reverse light wire? I believe it might be the problem but I cant find it on the wiring diagram.
Reverse light wires are LT GREEN
Here is the wire diagrams for your truck, Let me know if you need help .
My assuption about the reverse light wire was correct. For some reason there is a wiring harness that wraps around steering column and is attached to the brake pedal. Every time the brake was depressed it would rub the wire against a sharp edge and over time it shorted out. I rerouted the harness so it wouldnt rub anymore and it fixed the problem.
Thank for your help.