Patent ID: 8036786

Claim:
An on-vehicle control apparatus, comprising: a CPU for controlling an on-vehicle device based on a control program using various control variables; a rewritable non-volatile memory for storing the control program; a backup RAM for storing the control variables therein; a backup power supply circuit for supplying power to the backup RAM; a boot program for causing the CPU to rewrite the control program; an address changeover circuit for making a changeover in an execution address of the CPU to the boot program in rewriting the control program; and a memory rewrite unit, wherein: the memory rewrite unit outputs a rewrite signal for causing the address changeover circuit to operate, a command signal group including a command for activating the boot program, and an erasure command signal for erasing a diagnostic code after the control program has been rewritten; and the control program initializes the control variables in the backup RAM in response to the erasure command signal when being activated after having been rewritten.