We are dealing with two separate devices. The first is a “High Water Alarm” (HWA) and the second is a “Sensor”.
The HWA, mounted on the dash, consists of a 3-way switch (test, off, armed), a light and a 100 dB sound device. The test position of the switch should cause the light to turn on and a 100 dB sound to be produced. It is my understanding that this is independent of, that is does not test, the bilge sensor. If the test works as expected, then one can proceed to testing the sensor.
Flooring the bilge is a common way to do the sensor test. Other test methods are possible depending on the type of sensor installed. Flooding works with all sensors. Note that our boats are factory equipped with two bilge pumps, each nominally capable of pumping 750 GPH (perhaps model dependent). One would have to temporarily disable the automatic function of these pumps to carry out the sensor flood test. In addition, be aware that SPXFLOW electronic type sealed sensors have a built-in response delay,3 sec. or 8 sec. depending on which model, to help prevent false alarms due splashing. The expected response depends on the HWA’s 3-way switch position. If “OFF” only the red light should turn on. If “Armed,” then the expected response is both the light and 100 dB sound If this test fails to trigger the HWA, the sensor itself or the related wiring is at fault
