my 1992 truck is scaring me. my lights flicker when turned on. plus with the lights on or off the voltage gauge is under 14 and mover down and up. this is what i find strange though, when i was driving up to college at highway speed, the voltage gauge never got to 14, where it usually is. does anyone have any ideas what it could be. my brother checked the altenater and said it was good, could it be the batteries?