Hi Dave,
Everything related to the ECM (speedo, tach, cruise, exhaust brake, etc) worked just fine prior to shutting down the engine the last time I had run it. I came back a month later to exercise the coach only to find that she would crank but not start. The tach was not responding during the crank, and I had no check engine light test come on when switching the to key ON. I also could not get the ECM to give me any flash codes - not even the "all is well" 55 flash code. I had no engine data (like intake manifold temperature) on the Intellidrive with the key switched on. As far as I could tell I was not getting any signals from the ECM, and the coach would not start. After a lot of troubleshooting and as a last resort, I got down to removing the ECM J1 connector. I confirmed pins 52, 53 had good constant power, pins 65, 67 had good ground, and pin 70 had good switched power.
At that point in time I made the call that it was the ECM. I pulled it and sent it off for repair. The tech report diagnosis was "faulty battery" and that they could not retrieve the original settings off the ECM. So they said they programed it with the profile for an RV. They sent it back, I installed it, and here we are. The coach runs but the tach, cruise, and exhaust brake are inoperative.