Originally Posted by arokcrwlr

If you have 4x4 ESOF, then yes, the hubs (or in Ford speak, Integrated Wheel Ends/IWE's) engage and disengage.

Originally Posted by dmz01

So with this mod can I leave the truck in 4hi all the time and only control the front and rear with this new switch and the e-lock switch respectively?

Originally Posted by bb37

Where are the vacuum actuators located? At the hubs or at the inner ends of the halfshafts?

Originally Posted by arokcrwlr

I completed the mod that I initially termed the "2Lo Mod", but a better description would be the "Front Hub Disconnect Mod".

It allows 2Lo by disconnecting the front hubs while in 4Lo. Another benefit, if you have an e-locker, is the ability disengage the front hubs and effectively have the e-locker in 2wd to the speed limitation of the 4wd mode selected.

Why?

There are many benefits:

1. Useful in backing up a heavy trailer up an incline - easier on the transmission, etc.
2. It's great for maneuvering into tight places, especially if you need to turn the front wheels full lock - no driveline bind.
3. Any other scenario where you'd want low range on a high traction surface where 4wd would cause driveline binding.

Here's how it's done...

Refer to the ESOF schematic provided by dlh4x4 in the E-locker override thread. The wire from the solenoid to the TCCM needs to be switched to ground when 4wd is engaged to supply vacuum to the IWE which keeps the hubs disengaged.



Locate the IWE solenoid on the driver's side in the engine bay - it's next to the vacuum booster.



Per the schematic, constant power is provided by the GY-RD wire and the BN-BU connects to the TCCM and is the wire that needs to be cut.



I used a 30 amp relay to do the switching to help with trouble shooting and make it easier to correct a faulty switch in the cab. I mounted the relay to one of the vacuum booster mounting bolts and used a relay pigtail for the connections.



Then it's just a matter of making the appropriate relay connections and wiring the switch in the cab - all wire splices were soldered and covered with shrink tubing. Pin 30 connects to BN/BU wire coming from solenoid. Pin 87a connects to BN/BU wire going to TCCM. Pin 86 and 87 go to ground. Pin 85 comes from a switch that has 12v.

With the switch off, the system works like it should. Switch on, grounds the solenoid completing the circuit and keeps vacuum going to the IWEs. With the transfercase in 4x4 with the switch on will keep the wheel hubs unlocked.

All relay ground connections were routed to a ground point on the left side of the engine bay.



Connections cleaned up and routed...



Switch connection poked through the main wiring grommet on firewall...



Power for switch from a fuse piggy back harness...



I tested it at various speeds with/without the e-locker and it works perfectly. I need to re-do my switch - I originally mounted it in the little dash panel below the Sync badge on the dash, but with the area wasn't deep enough for the switch connections with the panel in place. I need to replace the little panel and find a different location.

If anyone decides to do this mod, I hope you find this useful.