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Trim Tabs-How do you know when they're dead?

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  • Trim Tabs-How do you know when they're dead?

    Will trim tabs lose functionality or will they just completely stop working when they their time is come?
    Formerly: Mako 236[br]Currently: 35\' Viking[br]Greenwich, CT

  • #2
    Usually the pump can be fixed or replaced very easily. If it's a Bennett, then the new pump may even fit the old mount holes. Have you checked your hydraulic fluid level? Have you had any oily residues at the bottom of your bilge?

    If you back you boat up a foot or two on the trailer, you should easily be able to run them up and down a check the range of movement. I know that mine don't work because that [email protected]#% control toggle (switch) shorted out. Is the pump getting electricity?

    Things to think about before losing hope on them.


    18ft MonArk tri-hull: 140HP Mercruiser Alpha One - still in be continued[br](I know it\'s not a Mako, but hey, its mine!)[br] Time\'s fun when you\'re having flies![br]president/hostmaster:[br]P.Ring Technologies[br]Cornerstone IT, LLC[br]LOUISIANA WEB HOST, LLC.[br]CompTIA Certified Professional A+/Network+ // Microsoft Registered Partner


    • #3
      On my Bennnetts I would hear a click from the motor when I moved the joystick, but that was it. Tested electrical connections with a voltmeter at the pump and everything was normal. I called Bennett on a friday and had a replacement motor by Wednesday the next week. The following is plagerized from warthog from a previous discussion on tab troubleshooting that I used as guidance when testing mine:

      "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


      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:


      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.

      6. Check to see if there is a relay in line on the wiring harness near the hydraulic power unit. If there is it is an Interrupter Relay (IR1000). It prevents the system fuse from blowing if you try to actuate one trim tab up and the other down at the same time. After you test as outlined above, try removing the relay from the wiring harness and retest the unit. If it works the IR1000 will need to be replaced."
      Danny Facciola[br]1987 231 Suzuki 225[br]Edgewater, MD


      • #4
        Thanks guys...I'm going to try some of these tests this weekend when I get back in town. I'm landlocked in Omaha right now! Cyclops, you may have hit the nail on the head! I have noticed a slight oily residue in my bilge. (I have an inboard, but other than the lubricant I occassionally spray on her moving parts, she is dry.) I will have to investigate further this weekend. I can feel the tabs moving slightly in my hand when someone manuevers the control, however, the tabs don't feel like they're putting out enough force to stabilize the boat underway.
        Formerly: Mako 236[br]Currently: 35\' Viking[br]Greenwich, CT


        • #5
          If it is a Bennett system, they are pretty good about replacing the pump for free unless it is really old. I remember buying a system at the Dania Marine Flea Market that did not work. I called them and they sent me a new pump. Great customer service.
          Sarasota, Florida