The relay is an automatic control device that when the input quantity (electrical, magnetic, acoustic, optical, and thermal) reaches a certain value, the output quantity will jump and change. The automotive relays are relays used in automobiles. These types of relays have large switching load power, high impact resistance, and high vibration resistance. The power supply in the car uses 12V, and the coil voltage is mostly designed to be 12V. Because it is battery power supply, voltage instability; harsh environmental conditions, suction voltage V ≤ 60% VH (rated working voltage); coil overvoltage allows up to 1.5VH. The coil power consumption is large, generally 1.6 ~ 2W, higher temperature rise. The environmental requirements are rather harsh: in the engine compartment, the ambient temperature range is -40°C to 125°C, and the ambient temperature range in other locations is -40°C to 85°C; the relays used in the engine compartment must withstand dust, water, and salt , oil damage; vibration, shock is quite harsh.