Is this for a toad?
Looks like a schrader valve
Going to have to follow it and see where it goes.
Definitely not for a towed. That is something that you put air in. Like posted above follow it. Not factory maybe to add air to the wet tank.
Dig the dirt out before using,looks like the end has dried mud.
Are there compression fittings on the hose side? Hard to see from the pic the type it is. It wouldn't make sense to be a schrader valve at the rear when there is a connection on the right side. I am leaning for a toad. Where does the line connect? Do you have something with a quick connect that you can attach and test what happens if you push the brake pedal? Also, you may have to remove the left side to connect to it.
Then again, I may be completely wrong, but I'd at least check out the above if it were mine.
It looks like a schrader valve to me also with a valve cap on the end.
Check where it goes.
Definitely for the air shocks
You really need to trace that line to see exactly what it is.
Were it OE, we could tell you. Installed by a previous owner-- no so much.
Thanks guys, I didn't realize it wasn't OE. I'll follow it next time I have the coach blocked up and report back.
Yup, NOT OE. Instead, PO (Previous Owner) or his minions.
It just comes out of the governor. Anyone have a thought on what it's intended use might be?
The 3 bottom threaded "reservoir" ports on the D2 all communicate directly with the wet tank. See link below.
If you connected the other end of the hose to a external air compressor, you could ADD air to the wet tank.
You could also use the other end of that hose as a source of air to supply wet tank air pressure to another device, or perhaps to inflate something.
You could attach a pressure gauge to the other end of the hose to monitor wet tank pressure. This is a handy diagnostic tool when chasing air leaks!
http://www.plazafleetparts.com/uploads/2/1/9/0/2190100/d-2_governor_maintenance.pdf
Might be for towing the bus with outside air .