On-vehicle electronic control device and a method of detecting a failure thereof

摘要

An on-vehicle electronic controller which controls the operation of a device of an automobile or an internal combustion engine is disclosed. A relay intermittently supplies power to a controlled apparatus. The controller first causes the apparatus to be operated for a predetermined period of time while the relay is off, thus ensuring that any residual voltage at the relay terminal is discharged. After the predetermined time, the relay terminal voltage is compared to a predetermined voltage. If the voltage is greater than the predetermined voltage, it is determined that the relay is welded shut.