When driving truck the GEN light comes on, then the battery gauge bounces back and forth. Been going on for weeks. Then when you turn off the vehicle and try to restart, the truck is completely dead, wait about 15 minutes then starts and everything fine. Well this morning it happened again but now the truck will not start at all. Dead as can be, can't even jump it. Please Help, mom needs help. Got alternator and battery checked both are good.