An electronic control device (20,20a,20b) includes one or more substrates (21), a casing (C), a plurality of circuit blocks (30,40,50), a common wire (23), a plurality of branch wires (31,41,51) and two interrupt wires (24,34). The circuit blocks are disposed on the substrates and the substrates are disposed in the casing. The common wire is shared by the circuit blocks. The branch wires are respectively coupled between the circuit blocks and the common wire. The two interrupt wires are respectively coupled with two of the common wire and the branch wires for overcurrent protection of the circuit blocks.