High pitched warning buzzer

[jfe1222]

Hi have a late 80's early 90's 90hp mercury outboard. Getting a constant high pitched warning buzzer. Buzzer comes on as soon as I turn key to power without the motor running. Expect a bad temperature sensor. Can any tell me how to check the sensor and if bad how to replace it? Not sure where the sensor is located.

 

[beckerjs]

Disconect the wire on the sensor and the horn should stop, the oil tank sensor is known to fall apart and trigger the horn. jb