My Road Kings was doing this and it ended up being a cold solder where the battery holder attached to the board. What Gnatty said to check is good and make sure you check voltage all the way to the battery holder. I had to wiggle my battery holder to get the volts to drop in and out. So mine was intermittent if that makes sense... I ended up putting a remote holder on, figured if I had to mess with it I should move it off the board, that's my 2 cents
-Jim