[RussWhite]

I will follow up a bit with my experience. The pin associated with coolant low was clearly corroded and all others looked new. I have no explanation for that. As I mentioned earlier, I cleaned it up and it was fine for a while. But, it came back. So, I ordered new sockets and replaced the corroded one. I think the real issue, once I got a close look at the old socket, was it had lost its spring tension and was not pressing against the rectangular pin.
Another option you have is to ground that socket. The coolant level sensor pulls the ECM voltage low when coolant is present, but does not pull it all the way to zero. I confirmed this by installing a test wire on the coolant level low wire at the ECM. Grounding might solve your problem ( although you give up the level low alarm ) until you can deal with it. Changing the socket was not easy. The correct extraction tool and crimping tool would have helped, but I did without.
Another difference is the reaction of DDEC IV to coolant low. My coach goes into a reduced power mode, no cruise, but does not turn on the engine shutdown light and does not shutdown. This, to me, seems like a more rational thing to do than a shutdown. If coolant is really low, one can watch the temperature like a hawk and get coolant added before any damage is done.