Method and arrangement for providing redundancy in a vehicle electrical control system

An arrangement for providing redundancy in a vehicle electrical control system, comprising:

• at least a first and a second electronic control unit connected to each other through a first data bus, wherein the first electronic control unit is arranged to perform a functionality A and the second control unit is arranged to perform a functionality B, the functionality A being different from the functionality B,
• at least a first and a second transceiver each connected to one or more I/O-units through a separate second data bus, and
• a programmable switch arranged between the electronic control units and the transceivers and configured to selectively interconnect the first and the second electronic control unit with the first and the second transceiver, wherein the programmable switch is initialized to interconnect the first and the second electronic control unit with the first and the second transceiver, respectively, thereby allowing communication between an electronic control unit and an I/O-unit,
• wherein a further selective reconnection provided by the programmable switch is controlled by the first and the second electronic control unit based on a fault status of each of the first and the second electronic control unit and the ability of the second electronic control unit to perform a functionality previously provided by a presently defective first electronic control unit, the first electronic control unit is arranged to store program code corresponding to a reduced portion of functionality B and the second control unit is arranged to store program code corresponding to a reduced portion of functionality A, and wherein the fault status of each of the first and the second electronic control unit is based on a control signal received from each of the first and the second electronic control unit, wherein missing control signal from the first electronic control unit is indicative of a faulty first electronic control unit and used by the programmable switch for interconnecting the first transceiver to the second electronic control unit, the second electronic control unit is arranged to also perform at least a selected portion of the functionality A previously provided by the first electronic control unit by activating, depending on from which electronic control unit the control signal is missing, the program code stored by the second control unit corresponding to the reduced portion of functionality A.