I can't speak personally for the CRJ (which I assume is similar), but this is for the Metro:
The Wheel Well and Wing Overheat Warning Light is linked to temperature sensors in the wheel well adjacent to bleed air lines and inside the leading edge of the wing root. The sensors are designed and located to detect a bleed air line failure. A steady warning light is triggered by sensors that detect a temperature of 350° F (177° C) in the wheel well or 450° F (232° C) in the air conditioning duct. A sensor in the wing root triggers a flashing light when temperature exceeds 250° F (121° C) in the wing leading edge. These temperature sensors will activate the applicable annunciator light whenever the threshold temperatures are exceeded, regardless of whether the heat source was related to a brake overheat/wheel well fire, air conditioning or bleed air malfunction, or an overheated generator wire heat.