My battery gauge began to intermittently be on and off each time I start the truck. Lately it has been off all the time. Checked the connection on the instrument cluster and all is well. Don't have wiring diagrams to go with my truck (which would be super if anyone knows how to get them?) so do not know where else to look. Anyone got any ideas how to fix this? Gauge is fine as it works now and then. Must a loose connection or grounding out?