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Hi Tabman, I have a 1993 233 Mako walkaround with Bennett tabs and the Port tab is sticking in the Down position. The HPU solenoid is sticking and not allowing the tab to come back up, I checked all the electrical connections and can only make the tab retract if you hold the switch and tap on the solenoid. It will go right back down if you hit the switch but will not return. The starboard side works properly. I would welcome any advise or help you could give me. Thanks for your forum on ThT and I will say that Bennett Products have ALWAYS performed flawlessly for me on my boats in the past and I hope this is something we can repair quickly!
Thanks, DaveMabes [email protected]
910 860-2433 h.
910 578-2258 c.
I believe the solenoid itself is fine, almost always if they are working to put the Trim Tab down they will work to bring it up. Most likely the solenoid is not getting enough power when you want to bring that side up. Although it's counter intuitive it takes more power to open the solenoid to bring the Trim Tab up than it takes to open it to put it down.
Is the pump corroded around where the solenoids screw into it? The solenoid receives ground where it screws into the pump body. You can carefully try unscrewing it, make sure that both Trim Tabs are fully up. Also take care since there is a plunger and spring inside. Then clean the threads, making sure not to get any debris in the valve. Replace the solenoid screwing it to only finger tight and see if it works. If the solenoid is so corroded that you cant unscrew it, that is likely the problem.
Also if the original connector plug is in the wiring harness near the pump, there may be corrosion inside the crimps that are limiting the volts going to the solenoid, and it is often worth replacing the connector or simply butt splicing the wires.
Below is standard troubleshooting, and you may want to try step 3 right at the pump.
Let me know what you find and I will be delighted to help.
Tom McGow
Bennett Marine
Fluid: Automatic Transmission Fluid (ATF) any type. Hydraulic Power Unit is self bleeding, running the Trim Tabs up and down 3-4 times will purge air from the system.
Fuse: 12 volt system use 20 amp in-line fuse on positive. (24v & 32v use proportionately smaller)
Red= Port Valve
Green= Starboard Valve
Blue=Motor Forward (pump pressure)
Yellow= Motor Reverse (pump retract)
Black on HPU=Ground
Orange on Helm=Control Positive
Troubleshooting
1.If one side is not operating reverse hydraulic lines on the front of the Hydraulic Power Unit to determine if the malfunction is in HPU or actuator / hydraulic lines. If after reversing the lines symptom shifts to the other side the malfunction may exist in HPU. If the symptom remains on the same side, malfunction may exist with the actuator / hydraulic lines
2. Is the unit receiving a solid 12 volts? Low voltage will some times cause the solenoids to not open preventing the tabs from moving even though the pump motor is running.
3. Conduct the following test:
Remove the wires from the helm control and touch together as follows:
Operation=Reaction
Orange (+), blue, red= Port trim tab down
Orange (+), blue, green=Starboard trim tab down
Orange (+), blue, red, green= Both trim tabs down
Orange (+), yellow, red= Port trim tab up
Orange (+), yellow, green=Starboard trim tab up
Orange (+), yellow, red, green= Both trim tabs up
If the trim tabs function correctly for each wire grouping then the switch is at fault. Also note that any loose or missing screws on the back of the switch (whether a wire is connected there or not) can cause the pump to malfunction.
This test may also be done right at the pump by substituting a "hot lead" for orange. There is usually a connector to the wire harness within a foot or so of the pump. You want to check this connection for corrosion. You may wish to cut the connector off on the pump side and try the test on bare wires.
4. If you suspect corrosion on the wire connector near the pump, cut it out, test as above and reconnect using butt splices.
5. If you conclude the problem is in the pump, contact me. Bennett Trim Tab Systems carry a five year warranty.
Thanks, I had previously done the troubleshooting, cut the connectors out, straight wired it, removed the ground wire cleaned and replaced the terminals. Now I have loosened, retighted and even added a temporary ground wire directly from the battery to the solenoids but this still did not get the proper actions from the tabs. Please recommend our next course of action. Thanks, Dave Mabes
Last questions, did you try reversing the hydraulic tubing at the pump? If you did and the problem changes sides, then based on the wiring tests you tried the system needs a new solenoid for that side. Part number VP1135, you can purchase one at most marine retailers.
Hi Tom, I do not think upon further inspection that I will be able to replace the solenoid because it is coroded and I can only get the top part of the solenoid to unscrew from the stem, the solenoid will not come completely out. Thanks, DaveMabes
Hi Tom, I do not think upon further inspection that I will be able to replace the solenoid because it is coroded and I can only get the top part of the solenoid to unscrew from the stem, the solenoid will not come completely out. Thanks, DaveMabes
Dave I think we found the problem! You have nothing to loose if you want to try to unscrew the "stem" with some force. I think it may be time for a new pump.
Bennett trim tab sticking HPU solenoid 
