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Moisture inside automotive lamps is universally accepted as a performance and cosmetic problem, particularly in the newer clear lens lamps. While simple open venting systems (tube type) can prevent liquid water intrusion, water vapor cannot be easily excluded from the lamp interior. Thus, under certain unavoidable conditions involving changes in environmental temperature, humidity, and lamp operation, a lamp may produce undesirable condensation on some interior surfaces. Efforts to optimize venting systems to clear this condensation involve controlling the air exchange through the vents. This air exchange is highly affected by outside airflow, a parameter complicated by wind, vehicle motion, and structures around the lamp. In this paper we report on investigations regarding how airflow around a lamp, both free and hindered by surrounding structures, affects the ability of common venting strategies to clear internal moisture.

Vented automotive lamps exchange moisture with the surroundings during steady state and transient conditions. An application of Fick's Law of Diffusion gives the mass transfer rate of a vapor A through a stagnant column of gas B for steady-state conditions. Automotive lamp ventilation is similar to this simplified problem given certain assumptions and where the vapor A represents moisture in the air at one end of the vent tube and the gas B is the air in or outside the lamp. This paper shows that the equimolar counter-diffusion problem, a solution for Fick's Law, has potential in reliably predicting humidity changes within an automotive lamp for static conditions.

Utilization of new technologies, such as LEDs, light guides, and electro-luminesence (EL), in courtesy lighting offers promising opportunities in styling, packaging, and functionality. Although these lamps are not as strictly regulated as other automotive lighting, considerable investigation is required to meet the desired styling and performance. In this paper we present the results of a study on running board lighting. This investigation was used to guide development of external courtesy lighting, where direct light, reflected light, contrast, and directionality are all design considerations.

Condensation of water vapor in exterior automotive lamps may cause corrosion related performance problems and cosmetic concerns, particularly in clear lens lamps. The amount and distribution of the water vapor inside the lamp depends on the environment external to the vent, as well as lamp characteristics. In this paper we report laboratory investigations focusing on two basic factors affecting internal humidity; humidity outside of the vent opening and basic placement of the vent hole on the lamp.