I noticed it has been a couple of days since you have been contacted. Have you been able to make any progress?
If not, I have a few suggestions. First, I realize you checked fuses, specifically fuse 14 in the fuse box (right kick panel). However, did you confirm there is power to and from it? If not, do that.
Next, I attached a schematic below, a portion of the same one Dan gave you. I highlighted the wiring between the fuse and the left rear light. The first thing I need you to check is if there is power out of the BCM (right side kick panel where the fuse is) in the gray wire with a brown tracer. If there isn't, unplug the BCM and check right at the pin for power. Also, check for corrosion or damage to the connector.
If there is power out to the aforementioned wire, there is a splice near the battery junction box. That splice may have failed. Locate it and see if there is power to that point. If that is good and power is on both sides of the splice, there is one more splice to check and that is at the rear light connection harness.
Let me know if this helps or if you have other questions. If you are able to follow that schematic, it should help to determine where the power is lost. Also, I believe the parking light relay would affect all the lights and not only the left rear.
Let me know if this helps or if you have other questions.
Sunday, November 14th, 2021 AT 9:33 PM