Trim Tab System Diagram - Part number and descriptions in table below.  Click to enlarge.

Trim Tab System Information and Troubleshooting

Note: Click here for Bennett Trimdicator troubleshooting tips.

Bennett Trim Tabs are build to rigid quality standards.   However, the marine environment is harsh.  So, in the unlikely event a malfunction occurs, here is some helpful information.

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 valve wire connections at helm control and quick-disconnect plug.
    - The following test can be used to help isolate the malfunction.

    - If the tabs function properly in each of the above combinations, check the helm control.  If during this test the trim tabs continue to malfunction, inspect the HPU.

3. If one trim tab operates and the other 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 the hydraulic tubing at front of HPU to determine if malfunction is in HPU or actuator / hydraulic connections.  If ,after reversing lines, the symptom shifts to other trim tab, a malfunction may exist in HPU.  If the symptom remains on the same side, a malfunction may exist with the actuator / hydraulic connections.

4. If trim tabs go down but will not retract -
     - Inspect for low voltage of the battery.  Check battery voltage while HPU (or another accessory) is running.  If voltage is less than 10 volts, valves will not open.
     - Inspect for disconnected or corroded connections on helm control and at quick disconnect plug.

Maintenance

- Periodically, check fluid level in HPU.  With trim tabs fully retracted, fluid level should be about 2" from bottom of reservoir (approximately 22 ounces).  To refill, remove the lexan cover and filler plug located on the front left hand corner of the reservoir.  FILL WITH ANY TYPE OF AUTOMATIC TRANSMISSION FLUID (ATF) ONLY.  Brands or types of ATF can be mixed.  Running the HPU with excess or lack of fluid will not cause damage.

- Periodically, check for clean electrical connections on the back of the control, HPU ground wire and quick disconnect plug. 

- Cold temperatures do not affect the trim tab system.   No winterization is necessary.

- SALTWATER ONLY - To deter electrolysis, a zinc anode should be attached to the top of each trim tab.  The zinc must make direct contact with the stainless steel.  In the case of trim tabs installed on the boat as original equipment by the builder, a bonding system may be utilized for your particular model.

- We suggest using anti-fouling paint to help protect the trim tabs from marine growth.  The secret to getting anti-fouling paint to adhere to your trim tabs is proper priming, and the best people to tell you what to do are the experts at the company that makes your anti-fouling paint.  We strongly suggest that you contact the paint manufacturer and tell them you are painting "304 stainless steel" trim tabs, then follow their recommendations to the letter!  Remember don't paint under the zincs.

- Unpainted trim tabs may acquire an orange discoloration.  THIS OXIDATION OF SURFACE CARBON MOLECULES IS NORMAL.  Orange coating can be cleaned off, but will eventually return.  Note: this discoloration should not be confused with the pitting and corrosion of electrolysis.