-N,N-Dimethyl-3–3-propanamine maleate and polymorphs of DNT-maleate, compositions of DNT-maleate and its polymorphs, processes for the preparation of DNT-maleate and its polymorphs, and processes for the preparation of duloxetine hydrochloride from DNT-maleate are provided. The switch can also have a multi-gap, interdigitated electrode for the generation of additional parallel filaments. Whether which of variable intake valve lift devices of the cylinder groups is abnormal is determined from control modes of the variable intake valve lift devices of the respective cylinder groups, and the relationship between that cylinder group, to which a cylinder being maximum in air-fuel ratio belongs, and cylinder group, to which a cylinder being minimum in air-fuel ratio belongs.