Load drive control circuit

摘要

A load drive control circuit (8) includes a drive circuit (10) for driving a load. A control circuit (9), connected to the drive circuit by diagnostic lines (L3a - L3d), provides the drive circuit with a control command (S1) that specifies an operation state. The drive circuit drives the load in the operation state specified by the control command, generates a diagnostic output (Sk1, Sk2) including diagnostic notification signals (S3a - S3d) 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 (36) 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 (37) checks whether the first and second diagnostic outputs are both normal to determine whether the diagnostic lines includes a failure or not.