[. . . ] This unit is designed for negative ground (earth) 12 V DC operation only. Before making connections, turn the boat's ignition off to avoid short circuits. [. . . ] A power antenna (aerial) without a relay box cannot be used with this unit. Memory hold connection When the yellow power supply lead is connected, power will always be supplied to the memory circuit even when the ignition switch is turned off. Use speakers with an impedance of 4 to 8 ohms, and with adequate power handling capacities to avoid its damage. Do not connect the speaker terminals to the boat chassis, or connect the terminals of the right speakers with those of the left speaker. Do not connect the ground (earth) lead of this unit to the negative (­) terminal of the speaker. To avoid a malfunction, do not use the built-in speaker leads installed in your boat if the unit shares a common negative (­) lead for the right and left speakers. note on connection If speaker and amplifier are not connected correctly , "FAILURE" appears in the display. In this case, make sure the speaker and amplifier are connected correctly. Check your boat's auxiliary power connector diagram to make sure the connections match correctly. You may need to switch the positions of the red and yellow leads in the boat stereo's power connecting lead. [. . . ] Warning if your boat's ignition has no ACC position The unit will shut off completely and automatically in the set time after the unit is turned off, which prevents battery drain. If you do not set the Auto Off function, press and hold until the display disappears each time you turn the ignition off. [. . . ]