| 摘要 |
PURPOSE: To add theft preventing function of high reliability to CPU backup function by stopping the changeover to backup action until confirming that an engine is started by a normal key switch. CONSTITUTION: When an ignition signal 1a is outputted and a start signal 1c is outputted from an input-output circuit 10, a backup authorizing device 8 receives these two signals, makes a backup authorization signal 8a high and authorizes the changeover to a backup mode. When a CPU becomes abnormal again after the backup authorization signal 8a is made high and reset signals 2a are generated specified times, a CPU failure detecting device 3 makes a backup changeover signal 3a high to switch to the backup mode so as to be able to secure required minimum vehicle travel. With this constitution, the changeover to the backup mode is not made unless normal engine control by the CPU is started so as to prevent the theft of a vehicle caused by the mulfunction of the CPU. |
