When you say you have no back lights, do you mean you have no lights in the rear at all, including brake lights, backup lights, and turn signals? Or just no back up lamps.
Either way we are going to have to start with checking for voltage through the circuit.
Here are some guides that will help with this:
I am attaching the wiring diagrams for the reverse lights and exterior lights.
Since this is a manual transmission and if you are just missing the reverse lights then I suspect the backup lamp switch is the issue.
I would just check the voltage coming out of it or jump it and see if the lights come on.
I attached the info for the exterior lamps as well so let's clarify what is happening and then work through the correct wiring diagram.
Images (Click to enlarge)
Sunday, October 10th, 2021 AT 8:25 AM