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Trim/Tilt sending unit

brettmarl

brettmarl

Regular Contributor
Launched boat today after fixing my tilt trim and noticed that the sending unit reporting trim status isn’t quite right.

It’s delayed - like it stays on 0 for the first 20% and then starts working (20% off from reality). I didn’t touch the sensor as part of my work other than unplug and reinstall wires. I wiggled it up and down to make sure it has full range but that didn’t help.

Will start with some electrical cleaner on the plug tomorrow. Seems unlikely it would suddenly “go bad” so wondering if anyone one has any ideas before I replace. Really don’t want to have to pull the boat out again!
 
The sending units can get sticky when sitting for a while. Not hard to check to see if that arm is working smoothly vs. sticking, all crudded up....
 
chawk_man said:
Also, in addition to Alan's comment, they do come loose. and get out of adjustment. Easy to check.
Click to expand...
what does 'loose' mean? the two bolts holding them on, or is there something else i'm missing?

mine looks perfectly mounted position-wise, bolts are tight and has full 180-degree range of travel. there is nothing interefering as far as i can tell (looks identical in position to port motor) and it doesn't feel like it's sticking anywhere in the swing.

hard to visually watch it in action as when the motor is trimmed down it's hidden by the bracket.
 
My latest theory is that given my tilt-trim rebuild had a little fluid-explosion at some point when i pushed a piston down with the motor off the pump - perhaps some hydro fluid got up onto the sensor and contaminated it. will pull it off and do a full clean up an then retry...
 
You are probably correct. Internally, it is just a simple rheostat that varies resistance. If you unplug it and hook it up to an ohm meter, then you should see a smooth variance as you move the arm. What I don't know is how that signal gets from the device itself to the console - that is, does the wiring go straight to the wiring harness to the console, or does it go through the ECU.
 
For my ak3 it presumably goes via the ECU - as it goes to both the analog gauges and over NMEA2k to digital displays.
 
Well.. I replaced sensor and all is good - but still not sure I understand what failed and why it was so suspiciously at the same time as working on tilt system.

Here are my findings in case it helps someone else …

New sensor - measuring resistance across wires

New sensor
Black-green:
Rest and open 4.97 KΩ ( assume this is the power feed and not variable sense value)
Black-yellow:
Rest 4.06 KΩ
Open 0.44 KΩ

Broken sensor:
Black-green:
4.97 KΩ
Black-Yellow:
Rest 5.15 KΩ
Open 0.073 KΩ

So clearly the variable resistor is shot as measures too low at the trim end which is consistent with what I get on gauges. Didn’t see any signs of fluid contamination.

Visually - part of the plastic housing that acts as a stop had snapped off (see photo). This seems to only come into play at the very top of the tilt range but perhaps the over extending damaged the spring or the resistor in someway.

803A2F3D-3215-4C18-B881-6CCA5C37460B.jpeg
 
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