Testing should be performed with the boat in the water, however you can initially confirm basic operation with the boat on the trailer.

Power the unit on. If the unit does not power-up, ensure the unit is fully seated on the mount and that power is available.

Make and models perform the start-up checks differently. For the most part, if no transducer is detected (or one is not connected), a message will indicate this. Some models will automatically go into a simulator mode after the initial screen times out.
Note: the transducer must be submerged in water for reliable transducer detection.

Typically, if a transducer is detected, the unit will enter "Start Up" or normal operation unless you choose another option. If the boat is in the water and no buttons are pressed, the sonar data will appear.

If the bottom is visible on screen with a digital depth readout, the unit is working properly. Ensure the boat is in water greater than 2' but less than the depth capability of the unit and the transducer is fully submerged. Remember the sonar signal cannot pass through air.

If the unit is working properly gradually increase the boat speed to test high-speed performance. If the unit-functions well at low speeds but begins to skip or miss the bottom at higher speeds, the transducer requires adjustment. Typically, the angle, height or location of the transducer needs adjusting. Refer to the appropriate transducer installation section for more detail.
Note: it is often necessary to make several incremental transducer adjustments before optimum high-speed performance is achieved.