Memory rewriting system for vehicle controller

A memory rewriting system for a vehicle controller is provided. The memory rewriting system transfers a first program from a rewriting device 11 to the vehicle to rewrite a second program stored in a memory of the vehicle controller 10 with the first program. The first program is transferred as data blocks. Each of the data blocks includes a program code field, a first address field and a second address field. The program code field contains a partial program code of the first program. The first address field contains a leading address of the memory in which the partial program code is stored. The second address field contains a leading address of the memory in which a following partial program code transferred by another block is to be stored. The data blocks are assembled in the rewriting device. Each data block is may be a fixed length or a variable length. When the data block is transferred to the vehicle controller, a first address in the first address field of the current transferred data block is compared with a second address in the second address field of the preceding transferred data block. If the first address included in the current data block is not equal to the second address included in the preceding data block, it is determined that the current transferred data block is not correct. The vehicle controller requests the rewriting device to retransfer a correct data block that has said second address in the first address field.