Re: Rear passenger blinker issue
How does it operate when you use the Hazards ?
If same, it may be a bad Switch since from my understanding the Rear Turn signals run on their own circuit after the Hazard/Multi-Function switch. If the flasher is working the other lights just fine and the problem is isolated with just the Right Rear, I would believe the switch is bad and/or has some short inside affecting the Right Rear.
***Well, just realized that the OP was from Oct. of last year. Hope you got it fixed.