SELF-DIAGNOSTIC DEVICE FOR VEHICLE

摘要

PURPOSE:To perform accurate reflection of a vehicle state during detection of abnormality by means of frozen diagnostic data. CONSTITUTION:A control unit 1 is provided with a CPU 101 and a RAM 102 to hold a memory content. The CPU 101 detects abnormality of mounted devices and when device abnormality is detected, diagnostic data is updated. When updating of the diagnostic data is not stopped, the content of the RAM 102 is updated by means of diagnostic data required for analysis of device abnormality at each given updating period. The updating period is shortened when the rate of change of diagnostic data is high. This constitution causes freezing of sufficiently reliable diagnostic data near a point of time when device abnormality occurs.