Trim sender malfunction

[nicksharpe]

Hi all. My trim gauge hasn't worked since I bought the boat in January so I thought it was time to do something about it.

I've replaced the gauge but no joy. None of the instructions I can find on various forums seem to relate to what I assume is my sender unit - see pic via this link [https://www.dropbox.com/sh/3bk6m8t3n...2gCotB7a?dl=0]. They want me to disconnect leads when mine seems to be sealed in, or trace wires into the engine, when they don't seem to go there. For clarity, there appears to be just one black lead connected to the unit's anchor screw (I assume this is an earth) and the brown and white wire which travels under the deck to the gauge.

Looking for any help on how to test, and probably subsequently replace, the sender unit.

Thanks in advance,

Nick

[Orwell boy]

have you felt it with your finger under there ,they often stick in the engine up position ,there is an actuator which you may need to wd 40 and wiggle a bit ,not guaranteed the issue but far cheaper than a new sender if it is the case

[spartacus]

Trim senders are fairly basic bits of kit. Have you disconnected it to take a closer look?

On Tohatsu engines (well 2-strokes anyway), they are just spring loaded. As the engine leg is raised, the plastic arm unwinds to relay the signal. Get the leg tilted up, disconnect and check the wiring. Not unusual for wiring to become corroded (normally green).

Incidentally your engine steering tilt tube looks a tad neglected. Left unattended it will cause issues down the line. Invest in a grease gun, get it dismantled, cleaned and reassembled. Sorry, can't help myself!

[GuyC]

Is it a 737 Max by any chance?

I'd suggest connecting the black direct to negative to rule out an earth issue.

Are there different flavours of trim gauge? I know for pressure, temp etc there are Euro or US gauges. Are trim gauges similar?

[nicksharpe]

The bloody screws which hold the sender unit won't come undone. I've squirted WD40 behind it and might have to leave it at that.

As to the engine steering tilt tube... It's very corroded, agreed. You wouldn't be able to point me towards some instructions for doing as you suggest, would you Spartacus?

Originally Posted by spartacus

Trim senders are fairly basic bits of kit. Have you disconnected it to take a closer look?

On Tohatsu engines (well 2-strokes anyway), they are just spring loaded. As the engine leg is raised, the plastic arm unwinds to relay the signal. Get the leg tilted up, disconnect and check the wiring. Not unusual for wiring to become corroded (normally green).

Incidentally your engine steering tilt tube looks a tad neglected. Left unattended it will cause issues down the line. Invest in a grease gun, get it dismantled, cleaned and reassembled. Sorry, can't help myself!

[spartacus]

Originally Posted by nicksharpe

As to the engine steering tilt tube... It's very corroded, agreed. You wouldn't be able to point me towards some instructions for doing as you suggest, would you Spartacus?

Stu at Dangar Marine made these videos just for you!

https://m.youtube.com/watch?v=bwh65xem33k

https://m.youtube.com/watch?v=h6ChE6ZmZfM

Disconnect the drag link and see if you can remove the steering. I'd do a general clean up, regrease and reassemble. Replacing the tilt tube is a bit excessive, however depends what you find.

[boristhebold]

The trim sensor units are generally simple bits of kit usually. You should be able to fault find relatively easily.

If it were me I would do the following;

Locate the trim sender unit and ensure A the mechanical functions work and that the arm does move against a bracket or tab somewhere. On my yamaha engine the tab which the sendor arm moves against has broken once before, some are plastic, replacements are metal brackets. also check the arm hasnt moved the other side of the sendor tab which can happen.

If good movement and sendor arm bracket / tab thing is good and positioned correctly then.

Cut the wires from the guage about 6 inches from unit, strip the ends, get a multimeter and test continuity from the cut black wire to wherever your main earth/ground is. If that is ok then consider the brown and white wires.

The brown and white wires would go to the trim sender unit which normally is just a simple potentiometer type of device with probably a mechanical arm, when the arm is moved by something the resistance changes which then is measured by the guage as a trim level.
Strip the ends of these two wires and connect both to a multimeter set to check resistance, then move the engine up and down, the resistance in the circuit should change, if it does change then that would indicate a fault with the guage itself. If it does not change then either a fault exists with the wiring from the sendor unit or the sender unit itself.

[nicksharpe]

Originally Posted by boristhebold

The trim sensor units are generally simple bits of kit usually. You should be able to fault find relatively easily.

If it were me I would do the following;

Locate the trim sender unit and ensure A the mechanical functions work and that the arm does move against a bracket or tab somewhere. On my yamaha engine the tab which the sendor arm moves against has broken once before, some are plastic, replacements are metal brackets. also check the arm hasnt moved the other side of the sendor tab which can happen.

If good movement and sendor arm bracket / tab thing is good and positioned correctly then.

Cut the wires from the guage about 6 inches from unit, strip the ends, get a multimeter and test continuity from the cut black wire to wherever your main earth/ground is. If that is ok then consider the brown and white wires.

The brown and white wires would go to the trim sender unit which normally is just a simple potentiometer type of device with probably a mechanical arm, when the arm is moved by something the resistance changes which then is measured by the guage as a trim level.
Strip the ends of these two wires and connect both to a multimeter set to check resistance, then move the engine up and down, the resistance in the circuit should change, if it does change then that would indicate a fault with the guage itself. If it does not change then either a fault exists with the wiring from the sendor unit or the sender unit itself.

Boris this is excellent. By far the best explanation I've had of how to fault find on this type of sender unit, thanks very much.

Problem one is getting these screws undone so I can check the little arm which must be hiding behind the unit. I'll keep at it and let you know how I get on.

Thanks again,

Nick

[paintman]

As it's a Mariner you may find that the sender looks like this, the white plastic projection fits into a slot.
https://www.ebay.co.uk/itm/193160641439
They are basically a simple rotary potentiometer as already mentioned. If the seal fails they fill with water & corrode away.

The screws usually seize & are likely to be an absolute pig to get out - if they don't shear in which case you're drilling. Had all that fun with mine, but as the sender was falling apart anyway & I replacing it I just broke it away to get heat on the screws.

[nicksharpe]

Originally Posted by paintman

As it's a Mariner you may find that the sender looks like this, the white plastic projection fits into a slot.
https://www.ebay.co.uk/itm/193160641439
They are basically a simple rotary potentiometer as already mentioned. If the seal fails they fill with water & corrode away.

The screws usually seize & are likely to be an absolute pig to get out - if they don't shear in which case you're drilling. Had all that fun with mine, but as the sender was falling apart anyway & I replacing it I just broke it away to get heat on the screws.

Yes! That's the very thing. I couldn't find it at all. Worth considering whether a trim meter is worth £90 when I've got a fully functioning neck which can turn my head round to look...

That said, it's annoying when things don't work. Cheers paintman, I'll keep working on those screws with the option to give up live in my mind.

Nick

[nw04jen]

Morning

I know an old topic but I have a sender and gauge with no instructions for a Tohatsu - where do I actually install the plastic sender arm please?
Inside the cowling or externally on the tilt part somewhere- cannot find any diagrams of the actual sender connected to the engine?

TIA

[Herman Melville]

Originally Posted by nicksharpe

Boris this is excellent. By far the best explanation I've had of how to fault find on this type of sender unit, thanks very much.

Problem one is getting these screws undone so I can check the little arm which must be hiding behind the unit. I'll keep at it and let you know how I get on.

Thanks again,

Nick

Did you solve?

I have. Yamaha 90a - the trim sensor did work but now doesn’t and I am trouble shooting.

It’s the kind with the arm that presumably moves a pot as the motor goes up and down.

The arm seems to be spring loaded which I suppose makes sense to return it to original position.

But what moves the arm? What is it connected to ? Does it simply get pushed by some part of the metal motor coming down or is there some kind of bracket or special ‘thing’ to move it ?

Any comments much appreciated.

[nicksharpe]

Originally Posted by Herman Melville

Did you solve?



I have. Yamaha 90a - the trim sensor did work but now doesn’t and I am trouble shooting.



It’s the kind with the arm that presumably moves a pot as the motor goes up and down.



The arm seems to be spring loaded which I suppose makes sense to return it to original position.



But what moves the arm? What is it connected to ? Does it simply get pushed by some part of the metal motor coming down or is there some kind of bracket or special ‘thing’ to move it ?



Any comments much appreciated.

Unfortunately I didn't solve it. Couldn't get the screws undone to see inside the sender.

[spartacus]

Originally Posted by nicksharpe

Unfortunately I didn't solve it. Couldn't get the screws undone to see inside the sender.

Spray on Plus Gas penetrating oil. Those Philips heads are in good condition too. Get yourself a impact screwdriver, use the right Philips bit which sits snug, a sharp hit with a hammer and that screw will come undone.