Patent ID: 7788005

Claim:
An electronic control unit assembled to a vehicle, the electronic control unit comprising: a nonvolatile memory capable of rewriting data; diagnosing means that diagnoses a vehicle device mounted in a vehicle based on data from the vehicle device and stores in the nonvolatile memory a diagnosis result indicating abnormality of the vehicle device after determining the abnormality; control data storing means that stores control data indicating whether storage of the diagnosis result in the nonvolatile memory is permitted; permission switching means that changes the control data in the control data storing means from non-permission to permission upon receiving a storage permission command transmitted from an external device; and storage permitting means that permits the diagnosing means to store the diagnosis result in the nonvolatile memory, when the control data in the control data storing means is indicative of the permission, wherein the electronic control unit is configured to transmit data in return to a fault diagnosis device, which is provided as the external device and in compliance with standards of OBD II, when a command inquiring kind of information, which the electronic control unit is capable of outputting, is transmitted from the fault diagnostic device, and wherein the command transmitted from the fault diagnostic device represents the storage permission command.