Hi guys. I am installing a rear view camera in my 2014 lwb 4motion and wired it to the reverse light on the left hand side but the voltage there is only 10.7 volts even with the engine running. That's not enough to power the camera on. I checked the tail light and only 11.5 volts. I connect a battery and all is well at 12.7 volts. What am I missing?