Garmin GPSMAP 238 Sounder User Manual

Page 109

Appendix A

Testing the Installation

While it is possible to perform some checks with the boat trailered, the boat should be in the water

to properly test the sonar portion of the installation.

Press the POWER button and the GPSMAP 188/188C/238 Sounder should power on. If the unit

fails to power on, verify that the wiring adapter is seated properly in the back of the unit, the Red and
Black wires are connected to the correct polarity, and that the fuse is installed and not blown. If the
unit is connected to a power supply that exceeds 35 VDC, a “Battery Voltage High” warning will be
displayed and the unit will turn off.

Since water is necessary to carry the sounder’s sonar signal, the transducer must be in the water

to work properly. It is not possible to get a depth/distance reading when out of the water. As the
unit powers on, it should immediately start showing the bottom. Verify that the unit is not in the
simulator mode. If the unit is in the simulator mode, make sure that the transducer is connected to
the wiring harness.

To test the transducer installation, gradually increase the boat speed while checking the unit opera-

tion. If the unit displays intermittently or fails to display, verify that the transducer is aligned parallel
with the bottom and if necessary, adjust the transducer height until the unit operates correctly. It may
be necessary to make several adjustments to ensure proper operation throughout the speed range.

NOTE: When adjusting the depth of the transducer, make the adjustments in small
increments. Placing the transducer too deep can adversely affect the boat’s
performance and put the transducer at greater risk of striking underwater objects.

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