The Raymarine Autohelm 2000 appears to have a power supply diode located immediately adjacent to the power connector inside the unit's housing. The purpose of such a diode would be to protect the unit from reversal of positive and negative terminals due to a failure to wire the unit corrected to the boat's power supply. Inside the unit's housing the incoming power connects to a two prong connector in the upper right hand corner of the housing. The outer terminal is the GND terminal. The inner terminal is the V+ terminal. Checking for conductivty from the GND terminals (lowest left hand side pin) of each of the the three dual inline package IC's to the outer terminal shows full conductivity with minimal resistance.
Unit would power up when connected directly to a 12v battery at the plug side of the weather proof connector. Unit would not power up when the two wire ends from the socket side of the weather proof connector were connected to the battery. Both the run from the plug side of the connector to the unit and from the wire ends to the socket side of the connector showed minimal resistance when checked with an ohmmeter. Used steel wool to clean the inside of each of the two sockets in the socket side of the connector. This fixed the problem.
When powered up, the unit beeps once and them begins to flash the single LED. Hitting the "AUTO" button changes the LED to be constantly illuminated. The push rod of the actuator moves about 7-3/4" from 4-1/4" extend at minimum to 12" extended at maximum. Unit takes about 12 seconds to fully extend or retract.
Next step is to find a way to test it aboard.
Wiring: