An accessory drive pulley assembly is configured to transfer rotational power from an engine crankshaft to one or more vehicle accessories. The accessory drive pulley has an inner race rotatable about an axis and having an outer surface. An outer race is located radially outward from the inner race and has an inner surface facing the inner race. A wedge plate is located radially between the outer surface and the inner surface. The wedge plate is configured to expand and contract radially to selectively lock and unlock the inner race with the outer race. When locked, an associated pulley can rotate at a different speed than when unlocked.