Bizzare Problem: Autopilot Only Works when Shore Power Plugged in...

[sgtPluck]

I have a very strange problem with the auto pilot on my boat: It only works if the shore power cable is plugged in (not very useful as you can imagine.)

If that is not plugged in, then when I flip the pilot switch on on the elecrical panel nothing happens, the LCD doesn't turn on and the wheel mounted motor doesn't do anything.

If I plug in the shore power cable and flip the pilot switch on - the LCD beeps and powers up, and the motor activates for a few seconds on the pedestal. i.e. it seems to be working fine.

In addition, it doesn't matter if there is any power coming through the AC power input. I switched the fuse off on the dock, and the autopilot still works. (Mind you I haven't tried pulling the dock end of the cable out and seeing if it still works.)

I have no idea what is going on here, or why my DC autopilot should have any connection to my AC circuit.

Does anyone have suggestions of what to test to see if I can troubleshoot this strange issue?


Thanks.

p.s. this did work at some point. When I did my sea trial before purchase the auto pilot was working.