Ordinary non-waterproof connectors should be inspected as waterproof connectors, and all connectors at the engine must be waterproofed. Quality requirements: After the connector is inserted, check whether the pin is withdrawn from the sheath, whether the connector vibrates, and whether the wiring harness is too tight (mainly at the connection with lamps, solenoid valves, etc.). If the connector is vibrating, the connector should be fixed (long-term vibration at the connector may cause the connector to fall off). For the screw-mounted connector, it must be screwed in place (you can hear a crisp sound when it is in place), otherwise it will be long. After the time runs, there will be a phenomenon that the wiring harness is in poor contact.