Abstract: A load drive control circuit includes a drive circuit for driving a load. A control circuit, connected to the drive circuit by diagnostic lines, provides the drive circuit with a control command that specifies an operation state. The drive circuit drives the load in the operation state specified by the control command, generates a diagnostic output including diagnostic notification signals each having an H level or an L level, and provides the diagnostic notification signals of the diagnostic output to the control circuit. A signal output unit outputs first and second diagnostic outputs respectively in response to the first and second control command from the control circuit. A diagnostic line failure determination unit checks whether the first and second diagnostic outputs are both normal to determine whether the diagnostic lines includes a failure or not.