Well my auto locking hubs don't work when in the auto position, 4X4 works fine if I manually lock the hubs but it doesn't go into 4 wheel drive in auto. so im assuming its a vacuum leak but not sure what is the usual culprit, so basically what is the usual cause of the auto part to stop working?
MacDougall
Usually suspect is a vacuum leak. One way to check is, turn on your heat/AC vent to come out the front of dash, get on the throttle hard, if the air output goes from the front vents to defrost, then you have a vacuum issue.
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check lines running down to the hubs. Sometimes ice and snow will dislodge vac hoses or there cracked, or dry dry rotted.
Also, if you have the "in-line" heater valve on the heater core hose, the gray vacuum line gets knocked off easily. If you don't have the "in-line" heater valve, then the gray vacuums line gets plugged into a nipple on the HVAC box.
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Here is a 42 page PDF on ESOF diagnose and repair.
http://www.powerstroke.org/forum/at...ents/general-6-0l-discussion/28338d1315014082-manual-locking-hubs-f350-esof.pdf
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http://www.powerstroke.org/forum/at...ents/general-6-0l-discussion/28338d1315014082-manual-locking-hubs-f350-esof.pdf
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Most common issues with ESOF not engaging (Just fixed mine):
-vacuum hose going from frame to hubs. Just replace the vacuum hose going to the hubs (its cheap like $4).
-leak at HVAC box - gray line popped off
-PVH solenoid valve not operating - replace. this is what my problem was.
What I started with was first make sure my vacuum pump was working, disconnected gray line going into HVAC box, yep had vacuum. Then I flipped with ESOF to 4x4 and quickly disconnected the vacuum line going to the hubs (right by passenger battery) and you should have vacuum going down there. If not then it is most likely the PVH solenoid. Make sure there is vacuum going to this (red tubing). Make sure there is 12 volts going to it (center wire). The two outer wires are grounding wires that complete the circuit for the center wire.
what helped me was watching 3 you tube vidoes on diagnosing ESOF not working. The one created by the factory ford mechanic was the best. That narrowed me down to the PVH solenoid not working and had to replace that.
-vacuum hose going from frame to hubs. Just replace the vacuum hose going to the hubs (its cheap like $4).
-leak at HVAC box - gray line popped off
-PVH solenoid valve not operating - replace. this is what my problem was.
What I started with was first make sure my vacuum pump was working, disconnected gray line going into HVAC box, yep had vacuum. Then I flipped with ESOF to 4x4 and quickly disconnected the vacuum line going to the hubs (right by passenger battery) and you should have vacuum going down there. If not then it is most likely the PVH solenoid. Make sure there is vacuum going to this (red tubing). Make sure there is 12 volts going to it (center wire). The two outer wires are grounding wires that complete the circuit for the center wire.
what helped me was watching 3 you tube vidoes on diagnosing ESOF not working. The one created by the factory ford mechanic was the best. That narrowed me down to the PVH solenoid not working and had to replace that.
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