Right before you plug the RCA cable to the PCM via the FAKRA cable in the back of the PCM, what did you do with the remaining red wire coming from the RCA end?

 

This wire needs to be spliced into a red wire in the main wiring loom and gives the camera power to work. At the other end where the camera is, you will need to splice the camera's red wire to the red wire on the video cable. The black cable on the camera (if there is one) should go to a ground.