Diagnostic system for a motor vehicle

Claim 1

In a diagnostic system for diagnosing an electronic control system of a motor vehicle, said electronic control system having sensing means for sensing operating conditions of said motor vehicle, control means for processing sensor data from said sensing means so as to calculate control data for controlling said vehicle, said first memory means for storing said sensor data and said control data, the diagnostic system having a diagnostic device and connecting means for connecting said diagnostic device with said electronic control system, said diagnostic device including a keyboard, a control unit for communicating with said electronic control system through said connecting means to read out said sensor data and said control data from said first memory means in response to a diagnosis mode inputted through said keyboard in accordance with programs stored in second memory means, and a display for displaying said sensor data and said control data read out by said control unit, the improvement in the diagnostic and electronic control systems which comprises: third memory means provided in said electronic control system for storing address numbers of said first memory means storing said sensor data and said control data respectively; and fourth memory means provided in said control unit of said diagnostic device, upon demand of transmission of said address numbers from said electronic control system, for storing said address numbers in said control unit when said diagnostic device is initialized, so as to enable immediate and accurate read out of said sensor data and said control data from said first memory means by designating one of said address numbers corresponding to said sensor data and said control data.