It might not get to the Autohelm. Further, you may have differences in amperage-voltage (Amps x Volts) which produce watts. Fluctuation may set-off the alarm as well as falling below the threshold amounts.

I'm just guessing based on recollection of others problems.

I'd check the connections of both the ground and positive leads at BOTH ends of each. Then I'd check the voltage while you're running. If you can measure the amps accross the autopilot unit.