So we have a 2014 Express cutaway that is an old airport shuttle bus. 6.6L LGH. The wait to start never comes on on start up, but the CEL will light for 15 seconds, and you cannot attempt to start it while the light is lit. When it goes out, you can then crank it. IF you try to crank it while the light is lit, it will crank for 1/2 revolution of the engine. That's it. Over and over and over, until you key off, turn it forward, and let the CEL light for the 15 seconds. I had originally thought THAT was the glow plug procedure, but now that it's cold in Iowa once again, I've checked the glow plugs and I have power TO the module, but no glow plugs have power to them. I have ZERO engine codes. Never have. Nothing for bad glow plug, OR bad module. I've tried to find a pinout to see if the ECM is communicating with the module, but have had no luck there, either.