No power to amp gauge or fuel gauge

When I turn the key to th ON position I get power to everything electrical inside. speedometer and tach needle comes up slightly, however, amp and fual gauge do not move at all. Overhead computer reads no fuel and gas light is on. All other dash and service lights come on as well. IT will crank but not fire up. Did this once before and it suddely came back on and started up but not this time. Battery? fuse? alternator? Did notice a thin black 10 fused wire near the driver side battery coming from the passahger side that is no connected to anything but don't know what it connects to.