Need more details.
the ignition has two positions (run & Start).
1. What happens when you turn the key to "Run"? Does everything work (gauges, radio, turn signals?)
2. When does it say "Check gauges" ...after you tried the "Start" position?
It does sound like a intermittent connection. You need to isolate it to the "run" side or the "Start" side. If the "Run" side is bad, it will prevent you from starting. If the start side is bade, the 12V stuff should operate normally.
2014 40QBH Phaeton DP Cummins 380HP ISL, Freightliner XC, 2014 Jeep Trailhawk TOAD
Blue Ox Aventa tow bar, SMI Air Force One -South Orange County Ca.