hey champ definately try the belt first, hopefully its not the alternator. Definately get the multimeter its your best friend for electrics. When you get the belt check the plug as well makes sure its clean fire her up and throw the multimeter on it should be reading between 13.5-14.8v approx. If its lower then your alternator is stuffed or you have open/resistance in your connections.PS if cleaning engine bay avoid getting degreaser on the alternator, good luck