Diagnostic method, diagnostic apparatus, and diagnostic system for in-vehicle electronic control unit

The invention discloses a diagnosis method, diagnosis equipment and diagnosis system of a vehicle-mounted electronic control unit, a diagnosis platform comprises a link layer, a transmission layer, a service layer, a client interface layer and an application program layer, and the diagnosis method comprises the following steps: communicating with the electronic control unit by utilizing the link layer; receiving and transmitting data of the electronic control unit after communication is established between the link layer and the electronic control unit by using the transmission layer; analyzing the electronic control unit data by using a service layer to obtain a plurality of requests; packaging the requests of the service layer by using the client interface layer to obtain any combination of a plurality of requests; and forming an application program layer by any combination of a plurality of requests provided by the client interface layer. According to the diagnosis method of the vehicle-mounted electronic control unit, the diagnosis platform is divided into the link layer, the transmission layer, the service layer, the client interface layer and the application program layer, each layer realizes a relatively independent function, and the software degree is improved by fully utilizing a network protocol through layering.