So did you put in a new flasher to see if it changes? or not?

Not yet, I'm gonna have to go tomorrow. I'll keep ya posted.

Alright, so update time. I replaced the flasher. Only thing different with flasher is that the blinkers no longer blink excessively, both sides blink as per working order, however the rear blinking action of the light still does not work. I did use a test light to test the socket, it passed the test. So, changed bulbs (both front and back), tested socket with test light and blinker side blinked, solid light side lit solid, replaced flasher and both sides blink evenly but rear blinker still does not blink.

If you have trailer light harness installed, you might want to check it to see if something got crossed/ shorted anywhere from the connector to where the trailer lights tie into the rear wires.

Another tip, try diagnosing problem using the hazard switch instead of the turn signal, and I believe on your truck the brake light and turn signal are the same bulb, so see keep that in mind as part of your troubleshooting.

I have tried that, hazard lights blink 3/4 lights. The only one not blinking is the non-working blinky light.