External power lost...

I seem to remember someone else posting about this, but I can't find it, so apologies in advance for asking again.

I've just returned from ten days in France and during the trip had to turn my engine on before turning on the Zumo 660. If I allowed the 660 to power up and then turned on the engine, it reported that external power had been lost and asked if I want to continue on battery power. The one time I chose "continue", it flattened the battery - but fortunately after I'd cleared Paris!

It's obviously not losing external power from the canbus, but there seems to be a software glitch somewhere on the unit telling it that it is. Any ideas?

Cheers.

Are you running it through an intercom, i.e does sound still come through the harness? When my mount packed up it wouldn't recognise external power and put the audio through the external speaker.

No mate, no intercom connected at all. It seems to recognise the engine start as (maybe?) temporarily cutting the power to the unit and assuming all is lost. I guess I may have a faulty unit. I'm running version 3.20 of the software.

Thanks for your thoughts