A hydraulic control unit that delivers hydraulic fluid to a limited slip differential includes a hydraulic control unit housing, a vent hole and first and second passageways. The hydraulic control unit housing has an accumulator housing portion that houses a biasing assembly and a piston. The accumulator housing portion forms an accumulator chamber with the piston. The vent hole is defined in the hydraulic control unit housing. The first passageway is defined in the hydraulic control unit housing. The second passageway is defined in the hydraulic control unit housing that intersects the vent hole and is oriented at a different angle than the first passageway. The vent hole is dual purpose permitting hydraulic fluid entry into the accumulator chamber through the second passageway while air is permitted to escape the hydraulic control unit housing through the vent hole.