Recently bought a twin diesel 2004 Cruisers 370 Express and when I turn on the AP it powers up and seems to work for a minute or less, then I get a "Rudder Failure" error message. The hydraulic pump is moving the rudders before the error message, so don't think it is the motor. I am wondering if it might be the rudder feedback device? Ideas or comments, please. Thanks.
On power on, it assumes the feedback unit is there, but when it moves the rudder and no change in feedback value, it logs the error. Depending on the box, you can emulate the feedback by compass angle on the bow. Not a real pretty line but better than nothing. Check that the feedback tie rod is connected. This is the usual failure if it's not installed correctly.
Also check/redo the connecti0ns from the rudder feedback unit (RFU) at the AP computer. It is a twisted pair under screw terminals at the AP computer IIRC, if not re-seat the connector a few times.