The drive worked for the remainder of last Fall and earlier this Spring, but the drive doesn’t work at all now -- the controller reads "drive stop". According to Raymarine and other online sources, that error means either the rudder position sensor isn't reporting a change in rudder position, or the motor is drawing too many amps (i.e. due to a mechanical failure or steering system jam). However I'm sure the RPS isn't the issue because rudder position is being properly displayed on the control head, and the steering system works freely and properly by hand. I had hoped last week's search for voltage drop would also resolve this issue, but since I resolved that it's getting good voltage and the AP gremlin persists.

However the motor does work (in both directions) when I remove the wires that normally connect the drive motor to the controller, and apply power directly from the 12v feed to those wires. Because of this I suspected the Raymarine S2G (the original AP course controller) and bought a replacement (ACU-200). I still get the same “drive stopped” error with the new unit. (expensive parts to swap) Clutch has always worked normally.

So now I'm back to the motor as prime suspect. It would be nice if it were just some internal transistors or brushes, but the Whitlock motor is a sealed unit that is basically welded and/or epoxied closed. Whitlock support is still inadequate (IMHO) in the US and I've yet to receive any help from them despite numerous tries (phone calls, emails, pictures). A replacement motor is over $2k from Jefa, and right now that looks like my best option.