[cuppie]

If you're absolutely certain that the CAN splices (twisted pairs) in the wiring harness (located by the CCM) are intact.... I would next suggest inspecting the CAN lines at each door - in particular, in the flexible boots between door & body. Given that you have a hard no-communication fault for the left rear door, start there.

Caution: While the door harnesses are simply snapped into the pillars, do NOT pry them out from outside of the vehicle! You'll break the retaining ring (ask me how I know....)
Instead, remove the pillar trim (it's easy!), and 'pop' the tabs with a flat-head screwdriver from the inside of the pillars.

 

[cuppie]

Not sure why you're saying the module is integrated with the window motor???
This is the door module from what I'm hearing:

This is commonly (and semi-incorrectly) referred to as the 'lock module.' It's just a door lock, has zero smarts in it.

And this is simply a motor for the window:

This is the window motor, yes. It's also the door control module. The control unit is what powers both the window motor, as well as the door lock motor (actuator.)

P.S. Also, I changed the door's lock actuator (first picture) and for some reason, it isn't getting power when I click "lock" or "unlock" on the key. All other doors are getting power to the lock actuators. What could be causing this? Wiring to it looks fine to me.

See above notes.
Also: Does the window on that door function?

 

[cuppie]

Glad you found it.

Welcome to bussing. One failed user (the window module) can (and, often will) corrupt (if not outright crash) the bus.