Abstract: During production line testing, some vehicles of a specific model exhibited gear-shifting failures. This article systematically analyzes the components of the electronic shift system based on its structure, including transmission diagnostics, electronic shift signal analysis, fault code investigation, actuator swapping tests, and fault freeze frame analysis. By constructing a shift system test bench to reproduce the malfunction, the investigation narrowed down the root cause to the transmission circuit between the electronic shift controller and actuator. Further analysis of the single edge nibble transmission (SENT) signal in this circuit reveals operational anomalies during actuator operation through oscilloscope monitoring. The signal characteristics confirm that interference is the primary cause of the failure. Subsequent optimization of the transmission circuit and retesting resolves the vehicle's gear-shifting issues.

Key words: vehicle malfunction; line-controlled gear shifting; unable to shift gears; SENT signal; line interference

摘要： 某车型的部分车辆在生产下线路试过程中出现无法换挡故障，文章根据车型线控换挡 系统的部件构成，对换挡系统的构成部件进行逐步分析，其中包括变速箱的排查分析、电子 换挡器信号分析、换挡系统故障码分析、换挡执行器对调排查分析、故障冻结帧分析，并通 过搭建换挡系统台架复现故障现象，逐步将引起故障现象的范围缩小到电子换挡器到换挡执 行器之间的传输线路这一范围。进一步对传输线路所采用的单边半字节传输（SENT）信号进 行分析，采用示波器采集换挡过程中的信号状态，发现 SENT 信号在换挡执行器的工作过程 中存在异常情况，结合 SENT 信号的特性，明确判定车辆故障的原因是由于该信号受到干扰 所致。针对上述原因，对信号的传输线路进行优化改进，并再次进行测试验证，解决了车辆 无法换挡的故障。

关键词: 车辆故障；线控换挡；无法换挡；SENT 信号；线路干扰