It has been two days since I've started my 86 k5.When I tried to start it today,the battery was totally dead.I jumped it and let it run to let the alternator charge up the battery.I then shut it off and restarted it to see if the alternator was charging the bat. and it was.Where should I look? Is this a common problem? The bat. is good but a circuit is open that is sucking the life out of it.