In-vehicle device, program, method for updating program, and in-vehicle updating system

A program that causes a computer configured to obtain an update program transmitted from an external server outside a vehicle and to perform processing for updating a program of an in-vehicle ECU mounted in the vehicle to execute processing for:

• obtaining an update program to be applied to the computer from the external server,
• selecting, as a substitute ECU, any in-vehicle ECU whose program is not an update target among a plurality of in-vehicle ECUs mounted in the vehicle, and
• performing activation processing for applying the obtained update program to the computer in response to an activation instruction from the selected substitute ECU.

A method for causing a computer configured to obtains an update program transmitted from an external server outside a vehicle and to perform processing for updating a program of an in-vehicle ECU mounted in the vehicle to execute processing for:

• obtaining an update program to be applied to the computer from the external server,
• selecting, as a substitute ECU, one in-vehicle ECU whose program is not an update target among a plurality of in-vehicle ECUs mounted in the vehicle, and
• performing activation processing for applying the obtained update program to the computer in response to an activation instruction from the selected substitute ECU.