Green air line cable use

Green is your supply for ABS and lights. Blue and red just charge and supply the air for breaks.

 

Since when do lights use air???

 

Since when does air supply abs electrical signs?

 

My guess is its likely for an air operated trailer accessory.

 

What does a red and blue airline do? How do they work?

 

The red air line supplies air to the trailer , releasing the parking brakes and filling all the tanks. The blue air line signal s the valve that applies the brakes (using the air in the tanks ) . Hopes this helps.

 

Your extra (green) line was for a lift axle or air power tailgate release , or any thing back there at was controlled by air.

 

Follow the line the other way and see what it's hooked to on the cab end. Likely as already mentioned it was for a trailer accessory.

 

Keeps the light cool.. Must be why LEDs stay cooler then the old style!!