2010 f350 vacuum problems

2010 f350 6.4. I'm having problems with vacuum solenoid. I've rebuilt entire front axle with new axle seals, u-joints, auto-hubs, etc. I also replaced the vacuum solenoid. Now for the problem. The vacuum pump runs continuously even when 4x4 not engaged. If I turn the knob to 4x4, you can hear the solenoid cycle and the hubs will briefly engage. If I plug the line to the vacuum solenoid, the pump will draw vacuum and shut off. Also if I connect line in to vacuum solenoid directly to the line out of solenoid (hub vacuum) the pump will draw vacuum and the hubs will stay engaged. Basically, it seems as though the solenoid is stuck in venting the vacuum even though it's a brand new solenoid. Is there a problem with the solenoid or is there a module that is failing to tell the solenoid what to do??

Sounds like a vacuum leak somewhere in the line between the two. Start at the solenoid and follow the line and check each connection.

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No leak there. If I plug the line coming from vacuum pump at the solenoid, vacuum pump draws a vacuum and shuts off. Same if I connect that line directly to hub line. It draws a vacuum and shuts off, locking the hubs. That's why I have to assume there's a problem with the brand new solenoid or a problem with a sensor that tells the solenoid what to do. I'm stumped!

If bypassing the solenoid it draws a vacuum, but with solenoid in place it doesn't, then I would suspect the solenoid?

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I know it's the solenoid, but it's brand new. I hear it cycle and it briefly locks the hubs then goes to vent mode when I activate the 4x4. Seems like either bad connection or a module. Just don't know where to go from here.

After further researching, I have found that the plug for the pvh is providing 12v to the center pin. But both of the side pins are providing a constant ground when selector switch is in 2wd. From what I can interpret, the side pins should only provide a short series of pulses of ground when selector switch is moved to 4wd or 2wd. One side pin is for engaging hubs and the other is for disengaging hubs. This is at least my interpretation. The question now is why I am getting a constant ground on the side pins? Is there a separate 4wd control module gone bad?? If anyone can chime in the help would be greatly appreciated!

Sorry, I haven't looked into it farther but I haven't heard of any other components causing issues like that.

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