I will check out the ground points and clean them up, but in the cold with heater blower running, wipers, headlights, radio etc., etc. the headlights are dim and the battery isn't getting charged and the lead tech at the shop is suggesting diodes in the alternator are failing. The battery is a year old, and consistently checks out as "Good- needs charge," so I need to get this charging system issue addressed before we are left stranded in the snow with a non-starting diesel again. I DO know the PO put "another" alternator in it a year before we bought it in 2010, but he didn't mention if it was new, rebuilt, used, etc.