Trim Sender Question

[briggs09hp]

Hello,

I have a 1995 Sea Ray with a Mercruiser 5.0L and Alpha 1. It is my first boat, and I am very happy with it so far (if all this rain would stop and the lake level would go down so my marina slip isn't under water any more). Anyways, I have a problem with the trim sender and gauge.

The gauge was stuck on the full up position. I figured the trim sender could be dirty and corroded, so I carefully took it apart and cleaned it up very nice and put it back together. But it still wouldn't work. Instead of having the sender replaced, which I found out was a pretty major job, I figured I would just run the boat for the season and have it replaced when I needed other outdrive work done, maybe this winter. I fixed the trim limit switch earlier and set it to the proper position, so there is no real danger in running the boat without a trim gauge.

But, to my surprise when I put the boat in the water the trim gauge started working. It was off calibration, but the gauge was no longer stuck in the full up position. I figured I would just go swimming when the lake got warmer, and take a screw driver with me and adjust the sender to calibrate it. But here in the finger lakes in NY, the lake is flooding so I got scared and pulled my boat out of the water. I figured it would be a good time to calibrate the gauge. But its stuck back on full up again.

Is there any reason why the trim gauge would work in water, but not when the boat is out of the water? Also, I believe that the trim gauge simply measures resistance. As the trim sender rotates, the resistance of the sender changes, causing the trim gauge to move. So if this is how it works, I was thinking: Could I just go to RadioShack and buy a variable resistor with a knob maybe? I would disconnect the trim sender wires, and temporarily wire in the resistor. Turn the key on (to power on the gauge) and play with the resistor to see if the gauge moves? If this is possible, does anyone know what the gauge is looking for as far as resistance? What is the ohm range of the sender? So i suppose what I am asking is: How many ohms is full up, and how many ohms is full down? This would tell me that the gauge works, and the sender is bad.

Thanks,

Matt

 

[sw33ttooth]

Re: Trim Sender Question

trim gauge...... basically the most useless gauge in the boat, next to the speedo i just installed a 7 set of gauges on my boat and the trim is off a half inch. as long as i know its down i could care less i have fish finder to tell me depth. with i/o you gota run the outdrive down any way so it doesn't really matter except for resale. if it really bugs you check the connections to the gauge its self maybe there loose and when you travel down the road it bumps it on and off?

 

[Xesvuli420]

Re: Trim Sender Question

well here is a video of me checking resistance on mine...
http://www.youtube.com/watch?v=QlWr89oc210

I never could get mine to calibrate correctly without cutting the calibrating groves out more. Mine is from Sierra Marine, and I don't believe I ever got a correct part from them, My replacement hydraulic hose was 9 inches longer then the OEM it was supposed to replace, my trim sender could not show full down without cutting into the mounts to allow for more turning, and many more.

I have never heard of one working in the water but not out. Like you said, its just a varible resistor. when the arm moves, it tells the gauge the change in resistance.

Personally I would replace it, but don't get your hopes up that its going to fix it, there are plenty of other ways for a circuit to gain resistance over time. Without getting a NEW gauge, NEW wire, and a NEW Sender, your just going to have to see what happens. I don't agree that its useless, especially if your doing water sports, but I wouldn't ever put 100% confidence in that gauge either. If I could get it working all the time, and get it adjusted where I know what places on the gauge mean what, then I would be happy. If its Sierra Marine, and their like the OMC Cobras, then your never going to get it to read full down without a dremmel tool.

Good luck, and if I can help, send me a PM

 

[Art Bernard]

Re: Trim Sender Question

I'd check for corrosion and loose connections. Than I'd break out the multimeter. If it's anI/O I'd see about getting it fixed so atleast you know it's down, if it's an outboard I'd replace the gage with a nice cupholder or maybe a clock.

Art