(at =F POWER CONNECTION ] 1. Battery disconnection First disconnect the power supply of the vehicle. This works out the best by removing the ground cable of the battery. doodad 2. Ground connection Connect the GND (ground) connection of the amplifier with the car chassis. Keep this cable as short as possible {not longer than 50 cm) and use a suitable cross section (AWG dice 6 10). Make sure, that the connection with the vehicle chassis is free of paint, dirt and dust. BATTERY HEAD UNIT 3.