I have been looking under the hood of my truck recently and noticed three vaccum lines that are not connected.

First a gray line coming from the passenger door area, ran in wire conduit, and comes out in the engine by the engine oil spout.

The second line appears to come up from the front passenger wheel well. It comes up between the battery and alternator.

The third line is capped with a blue cap. It starts from an electrical interface that is above the vaccum pump.

The trucks 4x4 automatic locking switch does not work from the inside. This will be something I will need to work on. Not sure where to start in identifying these, help me out.

 

Those go to your hubs for auto lock operation. The grey line is for the heater control valve.

 

Where do these line ends need to connect? Can you clarify what the line going to the eletrical interface above the vaccum is?

If the 4x4 hub is leaking will this drain the vaccum system? I was told when I bought the truck the automatic lock did not work.

 

The end with the blue cap on it, is supposed to be connected to the end with the 90 degree end open. That's what is supposed to engage and disengage your AUTO locking front hubs. The end with the grey hose is supposed to be connected to the heater control valve that's on the heater hose.

 

Easy (stupid) questions -

What does the heater control valve do? What should I see different when I hook it back up?

https://www.ford-trucks.com/forums/1...alve-leak.html

 

The heater control valve blocks off flow of coolant through the heater core when the mode selector is placed on the MAX A/C setting to boost cooling efficiency.