I have 2 mounted with boat power, Raymarine 630 and a Garman 45xl. I installed an external antenna for the 45 which helped to improve the accuracy. I used a light bulb with leads and a diode to verify power prior to hooking up. The diode only conducts in one direction which verified that the white was hot and black was the ground. One could assume red to be 12 and black ground, but it could have been wired incorrectly. Need to confirm continuity and polarity with a volt meter or with a simple rig like I made.