汽车电气线路中,一般均采用单线制线路,亦即:把电气设备及蓄电池的一个电极与金属车体联接,一般称作“搭铁”,利用金属车体作为电流回路的一根导线。这种联接法减少了金属导线的消耗,使电路简化。由于蓄电池及电气设备可以是正极搭铁,也可以是负极搭铁,所以汽车电系 In the automotive electrical circuits, single-wire circuits are generally used. That is, one electrode of an electrical apparatus and a battery is connected to a metal body, commonly referred to as “ground”, and a metal body is used as a conductor of the current loop. This connection method reduces the metal wire consumption, the circuit is simplified. As the battery and electrical equipment can be a positive ground, it can be a negative ground, so the Department of Automotive Electrical