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Johnson 90 Power Trim Intermittent Issues

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  • Johnson 90 Power Trim Intermittent Issues

    Hey guys- just stumbled across the forum today looking for some help with my problem. I'm a total boat noob and am having trouble finding information on this vast internet.

    I moved to the Charleston area a few months ago and bought my first boat - a 17' See Hunt with a Johnson VLS90. It ran great until about a month ago the power trim would start going out every once in a while. I would leave it alone and try again in a few minutes and it would be working again. Then this week it went out all together. It seemed like a wiring issue because the boat would start and run fine - and I would hear buzzing sounds coming from the relays. I replaced the relays and it still did not work. I started checking connections and fiddling with the wiring harness and magically it began to work again. However, it will still go out if the wiring harness is not held just right. Also, when it is not working and I hit the trim switch I will occasionally see sparks coming from where the wiring is grounded on the engine.

    All that said: I can not find anywhere where there is a short or a frayed wire. Is my best bet to buy a whole new harness and not spend any more hours on it? Has anyone else had a similar problem. I'm also a young guy and probably don't have the money to pay someone to fix it.

    Thanks so much guys.

  • #2
    Hi TSK90. What is the year of your Johnson outboard? And are you sure the model is a VLS90? Also, do you have an electric or a hydraulic tilt trim unit? I googled it and couldn't find that model number. I rebuilt my tilt trim unit earlier this year due to cost. Heck, I'm an older guy and don't have the money to pay someone to fix my boat! If you're boat is wired like mine, then the tilt trim is directly wired to the battery but the circuit is interrupted by several switches and relays and doesn't require the key switch to be "on" for the unit to be functional. What you describe does sound like a wiring issue, but to be sure, here's what I would do to check the electrical and rule out the parts of the system.

    Assuming you know how to use a multi-meter...set the meter to 20V. Also, ensure that your main battery switch is turned on. Begin the process of "ruling out" electrical issues.

    1. Disconnect the tilt trim unit from the harness. Stick the black needle in one end of the harness (coming from the relay) and the red end in the other side of the harness. Have someone press up or down on the tilt/trim switch on the throttle. Did you get a reading at or over 12V? If so, then the connection to that point is good and rules out any issues with the relays or that end of the harness.

    2. At this point, I would set a 12V battery near the tilt trim motor and touch the green wire from the tilt trim motor to one pole of the battery and then quickly press the blue wire to the other pole. Do it quickly as the tilt trim motor pulls quite a bit of amperage (especially if it's a hydraulic pump) and will spark if you do it slowly. The motor will either lower or raise. Switching wires to the opposite poles of the battery will do the opposite since the motor is a reversing motor as well. If it lowers and raises fine, then the issue is likely with the end of the wiring harness.

    Hope this helps and good luck.


    • #3
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      Check your relays you probably have a bad one there are only 2 of them. You should have the 3 ram hydraulic unit on that we also need the complete model #.