On-vehicle electronic control device

摘要

An on-vehicle electronic control device is provided, which includes an auxiliary microprocessor and subjects a microprocessor allocated to a main part of control to an external diagnosis, thereby improving reliability of performance. A microprocessor ( 110 a) including a nonvolatile program memory ( 115 a) into which a control program is written is serially connected to an auxiliary microprocessor ( 120 a) including an auxiliary nonvolatile program memory ( 125 ). The microprocessor ( 110 a) and the auxiliary microprocessor ( 120 a) functions in cooperation to control on-vehicle electric load groups ( 104 a and 104 b) in response to input signals from on-vehicle sensor groups ( 102 a and 102 b) and an on-vehicle analog sensor group 103 a. The nonvolatile program memory ( 115 a) and the microprocessor ( 110 a) are subjected to runaway monitoring performed by a watchdog timer ( 130 ) and to an external checksum diagnosis performed periodically by the auxiliary microprocessor ( 120 a). If an anomaly occurs in the run away monitoring, the external checksum diagnosis, and a checksum interval, parts of electric loads are cut off of power supply by load power relay ( 107 a).