Definition of the 3 wires of Mangoal Fuse box power adapterBlack Wire (GND/B-): Connects to the vehicle's body (usually Fixed on a metal screw). Red Wire (ACC): Provides power only when the vehicle's ignition is turned on. Yellow Wire (VCC/B+): Provides constant power, regardless of the ignition state. Parking MonitorAuto switch to Parking Mode and start to rccord instantly providing 24H protection for your car. Parking monitor must have "OBD Power Adapter" lf the OBD ll port is occupied, you can also get power through "Fuse Box Power Adapter", which can achieve the same purpose [Fuse Box Power Adapter] In order to match all car models, we have prepared a total of 4 sets of cables. There is always a set of cables that is suitable for your car.The interface of the SM is for connecting Dash Cam