Testing an Airmar Speed/Temp Sensor's Speed Function

The speed function of our sensors is best tested using an oscilloscope. However, a simple test can be performed using a digital or analog multimeter.

Our sensors are compatible with various manufacturers' products and can accept a supply voltage between 5 V and 12 V. The output square wave voltage generated when the paddlewheel rotates is equal to the input supply voltage. For example, if 5 VDC is supplied, a 5 VDC square wave is generated as an output; if 12 VDC is supplied, a 12 VDC square wave is generated.

Testing a Sensor with a Molded Connector

Note: If the sensor cabling utilizes a molded connector, please contact us to obtain a pinout of the connector.

For convenience, it may be easier to perform this test by supplying 12 VDC directly to the sensor from the battery when a molded connector is in place. Using the wiring diagrams to identify the correct pins, insert wires or test pins into the appropriate contacts to supply 12 VDC to the sensor and take measurements as described below.

Testing a Sensor with Open Wire Contacts

Connect the Speed Sensor to the Speed Display:
1. Measure across the red wire and shield (ground) on the sensor wiring. This is the DC supply voltage from the display unit, which must be between 5 V and 12 V.
2. Measure across the green wire and shield (ground) on the sensor wiring and spin the paddlewheel. You should read a fluctuating voltage (square wave) between 0 VDC and your measured input supply voltage.
3. Continue to measure across the green wire and shield, and slowly rotate the paddlewheel 1/4 revolution at a time. Each 1/4 turn should generate an on/off status as an output, i.e., 1/4 turn = 0 VDC, next 1/4 turn = supply voltage, next 1/4 turn = 0 VDC, etc.

Results

If you fail to obtain a supply voltage from the display unit, there is a fault with the display.
If you fail to obtain an output signal, the paddlewheel sensor is faulty.

If you need further assistance, please open a support ticket.