Rear left turn signal not working

Right turn signal works, hazards work, running lights work. I replaced the bulb, and relay at junction box works. We can hear a relay for the right blinker somewhere behind the left rear light, and hear nothing for the left stop/turn relay. Guessing it is bad, but cannot find anything to show how to access it. Chassis diagram shows this relay is specific to vehicles with tow packages, and is different from the combination relay at the junction box.