Recently, we were sailing with the engine (Yanmar 2GM) OFF and no key in the ignition, when the engine alarm buzzer started sounding a little. Within seconds, it got ouder and all three warning lights went on - engine still off! We also noticed that the needle indicating engine RPMs was moving between 5000 and 10000. Engine still off. We had to turn off all batteries in order to silence the alarm. When we switched the battery back on, same thing. We then started the engine (while alarms where still on) - all works fine and alarms went off with engine running. Then killed engine a - same effect, all alarms and lights came on. Maybe a faulty ground somewhere? Any other thoughts l?