Trim sender

roffey

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Nov 22, 2012
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2,206
Question for those in the know.
My trim indicator does not work. It jumps back and forth between full down and full up, then some times settles where it should be or gives the correct drive location. I was told by the marina I would have to replace the gauge and sending unit. Here's what I was thinking of doing, purchase a new sending unit and just replace the little puck unit on the out drive by cutting the wires on the old one and using dialect grease and shrink wrap. This way I wont have to pull the drive or fish wires? The gauge I will replace if it still does not work correctly.

is this a bad idea?
 
Last edited:

mr 88

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Nov 3, 2010
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2,180
I wouldn't even bother trying to fix it . If I'm in a boat with a working gauge , I never look at it . You should be able to feel what the hull is doing in relation to the trim of the drive . In most cases ,once on a plane , you trim up until you hear the rpms pick up to the point where it's starting to suck air . Now just drop the drive a little bit.
 

Chris1956

Supreme Mariner
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Mar 25, 2004
Messages
27,864
If the outdrive is a MerCruiser, replacing the trim sender is pretty easy. It should just be a couple of screws and a couple of wires to splice. Senders are simply variable resistors.

MerCruiser is kind enough to place them where they get wet and rot out. I would inspect yours first. Remember one side of the OD has the trim sender, the other has the trim limit switch. They look similar, so make sure you check the correct one.

You can check the gauge. Simply turn the ign on and ground the sender wire and the gauge should peg.
 

roffey

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Nov 22, 2012
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2,206
If the outdrive is a MerCruiser, replacing the trim sender is pretty easy. It should just be a couple of screws and a couple of wires to splice. Senders are simply variable resistors.

MerCruiser is kind enough to place them where they get wet and rot out. I would inspect yours first. Remember one side of the OD has the trim sender, the other has the trim limit switch. They look similar, so make sure you check the correct one.

You can check the gauge. Simply turn the ign on and ground the sender wire and the gauge should peg.
you are correct, they are identical... the one on the port side is the sender and the limit is on the starboard side, please correct me if I am wrong
 

airshot

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Jul 22, 2008
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5,100
Years back when I had my I/O, I replaced the trim sender a couple times, then realized they did not last very long. Learned to go by the feel of the boat and stopped wasting money to replace a gage that will soon go bad again !
 

roffey

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Nov 22, 2012
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I agree, I have never relied on the gauge. As stated above its all feel and sound. Its almost like flying, lol. I raise the outdrive and the boat comes out of the water and only about a foot of the boat is in... Love it.
 

roffey

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Nov 22, 2012
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FYI, my speedo does not work ether as the tube from the pitot is off.. Next time I change the impeller I will fix but the speedometer is also not really required. Tack, oil pressure and temp are all you need, IMHO.
 

airshot

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Jul 22, 2008
Messages
5,100
FYI, my speedo does not work ether as the tube from the pitot is off.. Next time I change the impeller I will fix but the speedometer is also not really required. Tack, oil pressure and temp are all you need, IMHO.
I gave up on pressure speedo's years ago, the GPS is always on with the depth finder ( which is very important in my area) and my OB is a two stroke now, so fuel gage and tach are all I need to watch.
 
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