Mitsubishi Denki Kabushiki Kaisha

Hiroyuki Mitsueda

Kohji Hashimoto

Katsuya Nakamoto

Masahide Fujita

An on-vehicle electronic control device 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 including a nonvolatile program memory into which a control program is written is serially connected to an auxiliary microprocessor including an auxiliary nonvolatile program memory. The microprocessor and the auxiliary microprocessor function in cooperation to control on-vehicle electric load groups in response to input signals from on-vehicle sensor groups and on-vehicle analog sensor group. The nonvolatile program memory and the microprocessor are subjected to runaway monitoring performed by a watchdog timer and to an external checksum diagnosis performed periodically by the auxiliary microprocessor. If an anomaly occurs in the runaway monitoring, the external checksum diagnosis, and a checksum interval, parts of electric loads are cut off of power supply by load power relay.

On-vehicle electronic control device

A microprocessor runaway monitoring control circuit with which self-diagnosis of a watchdog timer WDT can be carried out safely and cheaply even during operation of the microprocessor (CPU). A microprocessorsupplies first and second watchdog clearing signals WDand WDto first and second watchdog timers WDTand WDT, and when the both of the watchdog clearing signals WDand WDstop, the microprocessoris reset by way of a logical connector circuit. The microprocessorhas failure diagnosing meanswhich intentionally stops the first watchdog clearing signal WDand diagnoses the response of the first watchdog timer WDTon the basis of a monitor signal MNand stops the second watchdog clearing signal WDand diagnoses the response of the second watchdog timer WDTon the basis of a monitor signal MN, whereby diagnosis of the watchdog timers WDT, WDTis carried out without the microprocessorbeing stopped.

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Tokyo, Japan

Hiroyuki Mitsueda