I have a Duramax 6.6 believe it’s a 2012 no crank with key on ,dash come on but I don’t hear engine wake up or ecm ,also ecm was replaced new and programmed so was the key, started some diag by checking all fuses that send power to ecm and they do have power on both sides of fuse, I can’t connect thru obd it doesn’t see the ecm, I send 12 v to starter directly and it cranks starts slightly for 5 seconds then off it goes any tips would help
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