| CPC B60R 16/0232 (2013.01) [B60R 16/03 (2013.01); G01R 31/3277 (2013.01); H01H 47/002 (2013.01)] | 9 Claims |

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1. An electronic control device comprising:
a relay drive circuit that controls on and off of a power supply relay according to information about on and off of a power supply;
an electronic circuit that operates at a first power supply voltage supplied from a battery through the power supply relay; and
a monitoring unit that monitors the first power supply voltage when the power supply is turned off, and holds a monitoring result, the first power supply voltage reflecting presence or absence of fixing of the power supply relay, wherein
the monitoring unit includes:
a voltage detection circuit that outputs a signal of a level corresponding to a voltage value of the first power supply voltage, and
a storage that holds information indicating the presence or absence of a decrease in the first power supply voltage based on the signal output from the voltage detection circuit when the power supply is off as the monitoring result, wherein
the electronic circuit includes a processor that reads information indicating the presence or absence of the decrease in the first power supply voltage held in the storage and writes the information in the storage,
the processor detects fixing abnormality of the power supply relay based on the information read from the storage, and
the voltage detection circuit compares the first power supply voltage with a threshold voltage, outputs a high-level signal to the storage when the first power supply voltage is greater than the threshold voltage, and outputs a low-level signal otherwise.
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