Ford Ranger 2014 Massepunk for Pritschenelektronik

Hello, I have a mass problem with my ranger with the platform electronics or the lighting. If I use the mass from a lamp behind with a cable and hold on the platform everything fits. Otherwise I have no stand light and the turn signals flash on both sides if I only flash to the left or right. Now I ask myself where this electric is closed on the ground because I have unfortunately not seen / found anything! Otherwise everything works without a wall. Thank you in the foreground Mfg Manuel