12V DC power is required, to be connected to the supplied cable loom assembly. The power connection lead is clearly labelled. The +12V wire is black with a white stripe, and the ground wire is all black. If a cigarette-lighter type plug is used to draw power from the vehicle electrical system, then please ensure that the unit is unplugged when not in use, since the unit draws power whenever it is connected, even when the display is removed, and continuous connection for an extended period will eventually flatten the battery. Unreliable power supply is a common cause of problems. In the event of any problems please try an alternative 12V source in the first instance.