Vehicular diagnostic system using data from electronic control unit partic. for data communications protocol - has integrated circuit interfaced to ECU, with memory cartridge ROM contg. diagnostic program for partic. vehicle to be tested, and design data for reprogramming interface

摘要

The diagnostic system for a motor vehicle has various sensors for monitoring different operating conditions, and an electronic control unit (ECU). The latter responds to vehicle operating signals for controlling the vehicle and for producing control signals for various actuators and indicating lamps. The system reads out data in the electronic control unit, and transmits the data. A diagnostic device responds to the control signals for diagnosing the electronic control unit by comparing the transmitted data with normal data stored in a memory. A memory cartridge is detachably connectable to the diagnostic device and stores the various diagnostic programs and communications protocols. The diagnostic system has an interface circuit in the memory cartridge which is directly connectable to the electronic control unit. for matching a logic function corresp. to each control signal and generates a communications signal. A memory stores various logic programs, and an in-system programmer governs the operation of the memory in response to the communications signal, and re-programs logical functions of the circuit with design information to precisely diagnose the vehicle at a high speed without changing the memory cartridge for different types of the electronic unit.