Trim sender

[jusfish]

Hello everyone. I have a 1998 Yamaha 150 on a Skeeter and I’m having trouble with the trim gauge. I’ve checked the gauge itself and it seems to work when I jump the “S” terminal to ground. When I connect the trim sensor I get no response— the gauge is always pegged in the up position no matter where the sender is in its rotation. Thinking it was the sending unit I bought another one off eBay. Measuring the resistance across the sender it goes from 5 to 714 on BOTH of the sending units I now have. From what I’m reading online they’re supposed to read from 110 to 410, is this right? I would think that I should get some movement on the gauge as I rotate the sender arm through its range?
Any guidance you can give me would be greatly appreciated.

[McQuaig]

FYI: My trim gauge is always in full UP position with key off. It reads accurate with key on. You may just have a bad connection somewhere...

[yam911]

First measure the sender at the sender itself. Resistance and voltage. Voltage on the orange wire terminal should be ~ five volts.

Then measure the resistance of the pink wire at the trim meter.

[RDOCK]

VERY CONFUSING !

[yam911]

VERY CONFUSING !

How so?

[jusfish]

So now as i look at the plug in connection the trim sender has 4 wires as follows: in the plug--top right/black, bottom right/pink, top left/orange, bottom left/light grey that ends in a bullet connector. Coming from the console the plug is: top right/black, bottom right/pink, top left is empty, bottom left/green. the bullet connector is a separate wire that is light grey. So sender to console is: black to black, pink to pink, orange to empty, and light grey(bullet wire on the sender side( to green (on the console side). So the orange wire on the sensor doesn't connect to anything, just an empty socket. Doesn't seem right to me.

[yam911]

Is the boat new to you? Does it have a Yamaha multi-function tachometer installed?

[jusfish]

The boat is a 1998 Skeeter 185ZXc. I bought it last year but didn’t have time to mess with the problem. It has the stock ZX gauge which is made by Faria I believe.

[yam911]

The three wire senders need five volts applied to them. Via the orange wire. If the sender is not getting voltage then that might be the reason the sender no workee.

Yamaha changed to a two wire sender in 2001 or thereabouts. You might be able to replace your sender so that it will then work with more modern trim gauges.

[jusfish]

So I wonder if this boat is supposed to have a 2 wire sensor. There is nothing to feed the orange wire in the harness coming from the console. I can’t find anything around the engine that could feed 5v. Maybe someone put a three wire on here and couldn’t get it to work so they just left it…

[yam911]

Your motor would have come with a three wire sender. Usually the five volts comes from a Yamaha gauge.

If no Yamaha gauge I don't know how (if ever) the sender was made to work.

[jusfish]

So I found a 5v source on the back of my fuel gauge, ran it to the back and tapped it into the orange wire from the sensor. I get some motion on the gauge now, but only the top 25% of the sweep. I have two of these sensors, having bought another one on eBay. They both read from 8-753 ohms moving the lever from one extreme to the other. I find it hard to believe that both read exactly the same and are failed UNLESS the are both the wrong senders? Are there any other variables I’m not aware of here? The boat is bone stock so I am baffled by this…

[yam911]

Have you verified at the sender that the resistance between the pink wire and the black wire varies from 582 ~ 873?

Have you verified that this same resistance variation is being seen at the trim meter on the pink wire?

Have you verified that 5 volts is making its way to the sender?

My guess is that you have the wrong sender.

And have you verified that you have a Yamaha trim gauge?

[jusfish]

As I stated these two senders read 8-753 ohms black to pink I do have 5 v now at the connection under the cowl. I will check to see what the ohm reading is at the gauge. My gages are all stock that came with the boat from the factory. They are NOT Yamaha, they are Faria. I would agree that the readings at the sender are suspect compared to what I am seeing they should be online. It’s just crazy that I have two of them and they read exactly the same! I can’t prove that they are the correct part number by looking at them but they match up with the picture of the 3 wire gauge that is shown with the Yamaha species part number. The odd thing is that the harness from the dash gauge to the sender does not have the 5v power wire in it. But the sender side of the plug has the orange wir in it����*♂️ Maybe I have a unicorn here…

[McQuaig]

When I bought my 02 Skeeter (used) it had a 2001 0X-66 motor that had been recently rebuilt. The trim gauge and one other thing (I think it was the temp or oil light) did not work. After frigging with it for a couple weeks, I started tracing engine wires and found two small (identical size/shape) connectors in the same area with wire colors not looking right. It turns out the two connectors were reversed by the re-builder. I switched them so the wires in and out match and everything worked. A long shot but worth looking for on yours...

[jusfish]

UPDATE: Got it figured out! I tracked the wires from the gauge all the way to the sensor, unplugging and cleaning every connection. The power wire to the gauge didn’t have continuity to the back. It has several connections as it goes behind the console. And it changes color too. Anyway one of the connections was a little fuzzy and by the time I got to the back I had power again and the sensor and gauge were synced up. Interestingly, the orange wire on the sensor does NOT have a corresponding wire coming from the front! Apparently it is supposed to plug into a blank hole on the harness plug. Thanks for your help on this. Process of elimination I guess…����