Comment Re:Surprising to me (Score 1) 159
The speedometer will be configured to respond to a specific CAN message.
For example, in J1939 the vehicle speed is contained in a message formatted as follows:
Header ------------- Bytes 1-8
18FEF100 __ ll hh __ __ __ __ __
The speedo filters messages which have the header __FEF1__ and convert bytes 2 and 3 into speed, then displays it.
The hackers devices merely blasts the bus with erroneous messages.
For example, in J1939 the vehicle speed is contained in a message formatted as follows:
Header ------------- Bytes 1-8
18FEF100 __ ll hh __ __ __ __ __
The speedo filters messages which have the header __FEF1__ and convert bytes 2 and 3 into speed, then displays it.
The hackers devices merely blasts the bus with erroneous messages.
