if you have power to the display unit, on the display you will see a small dot/period where your speed and temp will be displayed if you dont get that your unit has no power ( doesn't need to be in water to see this). If you do see that then the problem is power to the probe, or connection from the probe. change probe batt, check antena, put in bucket of water. If you dont get temp displayed then take cable off and make sure your cabel is cleaned off 8ft at end and in contact with rigger. That is if you have cannons with the short stop.