Can someone enlighten me on why I'm getting a code 41 & 47? I've run over the wiring & everything appears okay. I can put a meter on the battery terminals & it appears to be charging normally (13.7 volts no load). I have noticed that it appears I do have a voltage/possible ground problem but I have no clue where to look.. Doing things like turing on the headlights, flicking the window switches, and even turning the turn signals on makes the hum of the fuel pump change. In fact if you turn the signals on it changes in relation to the flashes. However with a meter on the battery there's no fluctuation there. Any ideas? I'm guessing theres some corrosion somewhere, but for the life of me I don't know where it's at.