Electronic Shift-On-The-Fly (ESOF) System

WARNING: This page is about a different car, the 2011 Ford Pickup, 2011 Ford F550 Super Duty, 2011 Ford F450 Super Duty, and 2011 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

The electronic shift 4WD system consists of the following:

Transfer case
Transfer Case Control Module (TCCM)
Vehicle High Speed Controller Area Network (HS-CAN)
Mode Select Switch (MSS)
Gearmotor encoder assembly
4WD indicators and 4WD system messages in the IPC message center
Constant Vacuum Hublock (CVH)
CVH solenoid and vacuum lines
Vacuum pump (diesel engine only)

Vehicles equipped with an ESOF system allow the operator to choose between 2WD and 2 different 4WD modes. The transfer case is shifted electronically by the TCCM based on the MSS position. Under normal driving conditions, the transfer case is in 2H (4X2), but when desired, the operator can shift into 4H (4X4 HIGH) or 4L (4X4 LOW). The operator can shift between 2H and 4H at any speed. To shift into 4L, the vehicle must be stopped or rolling less than 5 km/h (3 mph) and the transmission in NEUTRAL.

The message center of the IPC displays 4X4 SHIFT IN PROGRESS during a shift, then displays the system mode selected. If shift conditions are not met, the message center displays Information guiding the operator through the correct shifting procedures. If the message center displays SHIFT DELAYED PULL FORWARD, transfer case gear tooth blockage is present. To alleviate the condition move the vehicle forward approximately 1.5 m (5 ft) and if the condition occurs during a 4L shift, place the transmission in neutral to allow the transfer case to complete the shift and fully engage.

The ESOF uses CVHs to engage the front axles. The CVHs are automatically controlled by the TCCM using the hublock vacuum solenoid, which either applies vacuum to the CVHs (4H or 4L) or releases and withholds vacuum to the CVHs (2H). Diesel engine vehicles are equipped with a gear-driven vacuum pump that is mounted to the front of the engine behind the accessory drive cooling fan driver and is serviced as an assembly.