Is it a reefer trailer and not a dry van? Reefers have a green light that show the unit is working properly. I've never seen one on a true dry van trailer.
Someone posted on another site a question, no serious answers, about a round green light next to the ABS light on the side of a van trailer.
Purpose?
Serious answers only please.
tough to say, with out a proper picture. but our trailers do have the Hendrickson trailer tires inflation system. many times if it is inflating a tire (or two), or just doing a "systems check" we get a light, but most times, it is a white light.
check as another poster said, if it is a reefer, but then, as a reefer driver, you should have known that light means everything is working.
check to see if that trailer has the inflation system, maybe if it does, they simply went to a "green" systems check light bulb color.