You also may need to check the metal prongs inside the rj45 jack on the floorboard and on the amp and see if they are all straight and not mashed down or crossing over into each other. After time they get bent and sometimes dont connect or line up properly with the cable you are inserting. Be careful, because the prongs only bend so many times before they break. But, good news is the jack is available and replaceable. Attached file is how it should look. Good luck