Yes look like trim tabs.
Being in the electronics game for the past 20 years, I find one of the easiest and best ways to troubleshoot problems is to component swap if you're able. Looks like it would be a relatively easy task to swap actuators from one side to the other.
Swap the actuators. If the same one doesn't work and the other one does, it's the switch or wiring.
If the one that worked ceases to function and the one that didn't does now, it's the actuator itself.
Otherwise if too difficult to swap, a test light or Volt ohm meter to test the switch.
Honestly the switch or wiring/connections is the best probability for failure.
Gotta love the internet..........I am really unsure how those switches work...how do I start checking it?
1. If trim tabs do nothing . . . no movement . . . no sound from HPU:
• Inspect for blown 20 amp in-line fuse in helm control’s orange wire.
• Inspect for disconnected or corroded connections on HPU ground wire,
orange positive wire from helm control, and quick-disconnect plug.
2. If HPU runs but trim tabs do not move:
• Inspect for disconnected or corroded red and green wire connections
at helm control and quick-disconnect plug.
• The following test can be used to help isolate malfunction.
Remove wires from helm control and touch together as follows:
O range ( + ), blue, red Port trim tab down
O range ( + ), blue, green Starboard trim tab down
O range ( + ), blue, red, green Both trim tabs down
O range ( + ), yellow, red Port trim tab up
O range ( + ), yellow, green Starboard trim tab up
O range ( + ), yellow, red, green Both trim tabs up
If trim tabs function in each of the above combinations, check helm
control. If during this test trim tabs continue to malfunction, inspect HPU.
3. If one trim tab operates and the other one does not:
• Inspect for disconnected or corroded red or green valve wire
connections at helm control and quick-disconnect plug. (Red wire
operates port trim tab; green wire operates starboard trim tab).
• Reverse hydraulic lines at front of HPU to determine if malfunction
is in HPU or actuator / hydraulic connections. If after reversing lines,
symptom shifts to other trim tab, malfunction may exist in HPU. If
symptom remains on the same side, malfunction may exist with the
4. If trim tabs go down but will not retract:
• Inspect for low voltage of the battery. Check battery for voltage while
HPU (or another accessory) is running. If voltage is less than 10 volts,
valves may not open.
• Inspect for disconnected or corroded connections on helm control,
and quick-disconnect plug.
This general information is not intended to be complete. Please feel free
to call Bennett Marine to assist in solving situations not clarified or addressed
above. Bennett Marine customer service is available to help Monday through
Friday, 8am to 5pm Eastern time. (954) 427-1400.