An electrical unit includes a housing member, a cover configured to at least partially cover the housing member, a primary circuit board disposed in the housing, and one or more secondary circuit boards connected to the primary circuit board. A primary circuit board may include a plurality of connection sections. A secondary circuit board may be connected to a respective pair of connection sections of the plurality of connection sections, such as via a respective pair of interconnection headers. A secondary circuit board may include a connector that may extend into a corresponding connector portion of the cover. Each of the one or more secondary circuit boards may include at least one of circuitry and electrical components for a respective vehicle function of a plurality of vehicle functions.