I am trying to diagnose the ESOF on my 2009 F250 6.4L. I have watched the youtube videos and read a lot about this issue on this forum. I can operate the hubs by manually locking them and engaging four wheel drive. The drivetrain works. I assume it is a front hub locking issue but I am just a guy trying to stretch my dollar by fixing this thing myself. If this were the brakes or something I could seriously blow up I would have stopped and gone to a mechanic. So far I have taken the following steps:
1. Pulled the vacuum hose from the inline connector just before the hub vacuum intake connector. Tested both hubs by drawing 10 inches of vacuum with a handheld vac bleeder/tester. The hubs held the pressure on both sides. Note: Only heard one hub engage; not sure if that means anything given both sides held pressure.
2. Placed system back to normal. Pulled the vacuum hose from the inline connector just before the left
hub vacuum intake connector. Placed vacuum gauge on the end of the hose leading back to vehicle pump. Turned power on and selected four high to engage vehicle vacuum pump. Vacuum pump initiated and drew 15 inches. Pressure stayed at 15 inches for the entire time the vacuum pump was running. After approximately 42 seconds following the vacuum pump shutting off I heard a valve trip near the vehicle vacuum pump and the pressure fell of the hub to 0 inches. Returned system to normal.
3. Repeated step two on right
side. Exact same results down to the second.
4. Scratched my head as the youtube video did not show this. The video showed that the pressure would stay on the vacuum test gauge for five minutes or more.
5. Attempted to test the vacuum lines from the other end but could not figure out which lines to test as my truck differed than the truck in the video. So, at this time, I skipped to testing the PVH solenoid per service instructions from Ford. With key in on position, I jumped both outside ground wires to negative on battery. Did not hear anything from the PVH solenoid. I then tested the incoming voltage to the PVH and it was sitting at 11.25 volts more than the 9 volts required.
Given the above, I am thinking that it is the PVH solenoid. BUT what am I missing?? Is the process incomplete without having tested the vacuum lines from the other end near? I could buy the PVH but no returns. Any thoughts appreciated. I even encourage good nature ribbing.