Trim position sensor testing

[99yam40]

I think he deleted it due to it showing varying resistance on both sides could be confusing to OP

[boscoe99]

I need a specific procedure...READ #6 above....which test method is correct?

#6 saying org to blk should not change and manual is VAGUE...

Although you don't recognize it yet, the Yamaha manual does provide a specific procedure. For testing of the three wire sender at the component level. At the component level input voltage is not involved. The sender is tested solely by itself. Maybe on a bench. Not connected to the motor and certainly with the key not being on to provide voltage to the sender.

Having the sender powered would mean that you would be measuring for a voltage output. This would be a system level test. Yamaha does not prescribe a system level test and does not offer any specifications for same.

We are trying to determine if the sender by itself is within specifications or not, yes?

It might help if you know that a three wire Yamaha trim sender is a potentiometer. A potentiometer is a variable resistor with two outputs. Yamaha is having you check first one side and then the other side.

Put your multimeter on the resistance setting. Place one probe on the black wire terminal and the other probe on the pink wire terminal. Move the sender arm in one direction as far as it will go. Measure and record the resistance. Move the sender arm as far as it will go in the other direction. Measure and record the resistance.

Now move the probe from the pink wire terminal to the orange wire terminal. The probe on the black wire terminal remains there. Move the sender arm in one direction as far as it will go. Measure and record the resistance. Move the sender arm as far as it will go in the other direction. Measure and record the resistance.

Are the measurements that you recorded more or less in line with the values published in the service manual? Did the resistance values vary smoothly and consistently as you moved the sender are from one extreme to the other?
If so, the sender is good. If not, the sender is bad.

Hope that I have not further confused you.

[rodbolt17]

Boscoe posted a very good diagram.
note when testing O-B your simply testing a resistor. that resitance wont change, it is fixed.
testing P-B it should.
but I would simply check the ground and the 5V ref and the pick off V.

but that is just me.
the USN trained me well.

[smhamilt]

Finally had a chance to test the sensor system. The sensor is good.

orange to black = 5 volts
pink to black = variable 0 to 5 volts as I move the motor trim

I tested at the motor and then at the connector to the gauge.

So, the correct variable voltage is getting to the gauge through pink. Is the gauge serviceable or can anyone think of what to do?

[throrope]

Did you also check the connections at the gauge? And the power and ground to the console? I had a corroded inline fuse at the battery on the hot to the console that made for interesting diagnostics.

As to the gauge, I replaced our fuel gauge with a trim gauge. Many styles available. Boat Trim Gauge | Overton's

Upon comparision, the only difference between the two was model number and back plate for trim vs fuel. I could have saved money by just swapping wires and adjusting so 1/2 tank was level.