Mystery tube beneath brake master cylinder

[Racerlinn]

I cannot identify what this wrapped tube is coming up from some wrapped tubes or harness right above the drivers side front shock tower, pointing up towards and almost reaching the bottom of the brake master cylinder. It kinda looks like a vac tube, and that perhaps there is a missing fitting or additional tube that should connect to it. It has tape wrapped around the end.

 

[igozumn]

Maybe an old air line from the auto adjustable suspension? Does your Expedition have air ride, or formerly have air ride? I'd follow that line to see where it goes.

 

[Racerlinn]

Nope, no air ride.

 

[CaperCanadian]

looks like its running forward, have you traced where it goes?

 

[Racerlinn]

It appears to be the vent line for the front hub 4wd. No idea where it is supposed to connect - there is a fitting and another line somewhere.... Anyone know? The shop manual does not show.

 

[Racerlinn]

And this may be why (from F150 online for a 2004)....
"Further, each IWE has two vacuum line connections. There is a double rubber vacuum hose at each IWE. You cannot put the hose on wrong- one hose is larger than the other. The larger hose is the vacuum control line from the IWE solenoid, and the smaller hose is a vent line that runs up high in the engine compartment and is not connected to anything (hence, it is only a vent)."