Abstract: In order to solve the low-voltage unenergized failure of BYD Qin hybrid, according to the circuit diagram and maintenance manual, analyze the low-voltage energized process, and summarize the diagnosis process of low-voltage unenergized fault. Finally, taking two real faults of 2019 Qin hybrid as examples, according to the diagnosis process, through two real vehicle troubleshooting cases, the feasibility of the diagnosis method is verified, which provides a certain reference for similar fault diagnosis.

Key words: BYD Qin; Low voltage energized; Fault diagnosis

摘要： 为解决比亚迪秦混动车型低压无法上电故障，根据电路图和维修手册，分析低压上电 流程，总结出低压上电故障的诊断流程。最后以两起 2019 款秦混动的真实故障为例，按照诊 断流程，通过两起实车排故案例，验证了诊断方法的可行性，为类似的故障诊断提供一定的 参考。

关键词: 比亚迪秦；低压上电；故障诊断