Trim display not functioning on F115AETX

I have finally gotten round to looking at an annoying problem I have with my Yamaha F115AETX (2005 model). A while ago the potentiometer (trim feedback)on the leg seized up. Thinking that cleaning it up and putting it back would solve the problem. No way. The pot which is a two wire version has a ohm range of 415 to 115 ohms, but the display wont move till there is less than 149 ohms from the pot. At 149 ohms the leg is all the way down. I have done some checks on the back of the display and have found that for the bar graph to display no bars (leg at full trim down) it would need a resistance of 9.5 ohms. This seems way too low. I dont have access to another display unit, and from the cost of the darn thing I hope that its not at fault. Is there anyone with inside knowledge who can point me in the right direction. I'm an electronics tech!
Merry Christmas
Robin from down under
Forgot to mention, the display is the multi function dude, tacho,trim,oil and temp warning.

[boats.net]

We just run a jumper wire from pink trim signal wire on gauge to ground(on a 2 wire trim sender system), with key on trim gauge should read full trim. If the gauge reads full then sender is probably bad.

I have seperated the display from the trim sensor, and as I mentioned the ohmage of the trim sensor looks OK. I have not been able to find out yet as to what the correct ohmage value of the sensor should be, but if it was faulty I would have expected the sensor to read a much higher value. There are no glitches in it as you slowly rotate it.Do you know what the ohmic value of the sender should be. I'm ablout to crack the display unit open and have a look inside. I don't have anything to loose as at this point as I suspect a faulty display. Can't believe how much a replacment unit is!!!!
Robin

[dorf]

Why don't you substitute a "potentiometer box" for the faulty unit, to see what the display needs to function correctly. I've got one that I've had for many years that allows me to dial in what ever "ohms" I need.

My '06-50TLR was/is inaccurate as can be(analog). Seems to me that these systems are sort of pre-tombstone technology.

My Yamaha book shows 168-288 ohms for my sender.

If your gage works showing "Full bars", it would seem that the indicator is good and the sender is faulty.????

Let us know what fixes it.

Ya, did that one. For the bar graph to display one bar (full trim) the sender unit would have to be 9.5 ohms. That's way out of the range of the sender unit. That's why I suspect the display unit. As I mentioned previously, I'll crack the case on the dsiplay and see if the are any discrete components that could be faulty, otherwise I'm up for $300+ bucks.