应用层--诊断

[中文适用范围]： SAE J1939 系列推荐做法适用于轻型和重型车辆的公路或越野用途以及使用车辆衍生组件（例如发电机组）的适当固定应用。感兴趣的车辆包括但不限于：公路和非公路卡车及其拖车、建筑设备以及农业设备和农具。这些文档的目的是为车载电子系统提供开放式互连系统。这些文档的目的是通过提供标准架构来允许电子设备相互通信。 J1939-73 标识了用于车辆服务工具接口的诊断连接器，并定义了完成诊断服务的消息。指定连接器和定义消息的子集满足加利福尼亚州规定的 OBD II 要求。诊断消息 (DM) 提供车辆维修时所需的实用程序。 [外文原描述]： SAE J1939-73 defines the SAE J1939 messages to accomplish diagnostic services and identifies the diagnostic connector to be used for the vehicle service tool interface. Diagnostic messages (DMs) provide the utility needed when the vehicle is being repaired. Diagnostic messages are also used during vehicle operation by the networked electronic control modules to allow them to report diagnostic information and self-compensate as appropriate, based on information received. Diagnostic messages include services such as periodically broadcasting active diagnostic trouble codes, identifying operator diagnostic lamp status, reading or clearing diagnostic trouble codes, reading or writing control module memory, providing a security function, stopping/starting message broadcasts, reporting diagnostic readiness, monitoring engine parametric data, etc. California-, EPA-, or EU-regulated OBD requirements are satisfied with a subset of the specified connector and the defined messages.