4x4 issue
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Cross-Country
Joined: Feb 2015
Posts: 96
Likes: 3
From: Alabama
That did the trick. I had some work done by Ford a few months back, fixing an oil leak around the injector rail on the drivers side. I found the hub vacuum solenoid connector locking mechanism had been broke off and the connector not all the way seated. Once I hooked the solenoid back up, I immediately could hear a hissing sound of leaking vacuum. Inside the protective wrapping on the upper vacuum line coming off the solenoid I found a snapped vacuum line. Fixed the broke line, and all is good with auto hubs once again. Thanks to all for input and to thomabb for the schematic.
New User
Joined: Jun 2017
Posts: 7
Likes: 0
I have a new Superduty and it is the first vehicle I have had in over 30 years with manual hubs. My question is once 4wd is engaged and hubs automatically lock, is there a way of unlocking them without doing it manually ?
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Cross-Country
Joined: Feb 2015
Posts: 96
Likes: 3
From: Alabama
if you have your hubs in auto, and select 4H or 4L in the cab, your hubs should lock. The only way to unlock your hubs at this point is to go back into two wheel drive in the cab. If you have your hubs in the Lock position, they are always locked until manually turned back to auto.
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Cargo Master
Joined: Apr 2010
Posts: 2,405
Likes: 4
Do you have the lever on the floor or a switch on the dash to put the truck in 4X4?
Cargo Master
Joined: Apr 2010
Posts: 2,405
Likes: 4
Your system is known as ESOF (electronic shift on the fly). The switch is the control to engage/disengage the transfer case and lock/unlock the front hubs. Without doing some modification, you can't unlock the hubs while the transfer case in in 4X4.
In the older trucks, you could unhook and plug the vacuum line running to the hubs. They would function like manual hubs at that point, giving you the option for 2-Low. What year is your truck?
In the older trucks, you could unhook and plug the vacuum line running to the hubs. They would function like manual hubs at that point, giving you the option for 2-Low. What year is your truck?
Thread Starter
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Cross-Country
Joined: Feb 2015
Posts: 96
Likes: 3
From: Alabama
Your system is known as ESOF (electronic shift on the fly). The switch is the control to engage/disengage the transfer case and lock/unlock the front hubs. Without doing some modification, you can't unlock the hubs while the transfer case in in 4X4.
In the older trucks, you could unhook and plug the vacuum line running to the hubs. They would function like manual hubs at that point, giving you the option for 2-Low. What year is your truck?
In the older trucks, you could unhook and plug the vacuum line running to the hubs. They would function like manual hubs at that point, giving you the option for 2-Low. What year is your truck?
Posting Guru
Joined: Jun 2014
Posts: 959
Likes: 10
From: Medford, OR
What would happen if you forgot to lock the hubs and moved the switch to 4WD at 30 mph? What gets the driveshaft and axle shafts up to speed before the transfer case tries to shift?
Hotshot
Joined: Apr 2013
Posts: 10,121
Likes: 657
From: NH
Just to confirm, all the 6.7L Super Duty trucks have full electric-servo operation for climate control...even those "manual" climate control systems in base model trucks. So you won't be able to determine a vacuum problem based upon climate control operation.
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