Probably just a coincidence, but I had almost the exact same scenario with my 818 after I started it this week. I could write a long story, but the bottom line is that one of the pins on the 3-pin connector on the alternator is broken off. The pins are rusty and it must have been brittle and broken off when I disconnected and reconnected the alternator. You could have the same issue, or something similar like a loose connector. Good luck tracking it down.