2021 Ford F-350 Owners Manual - Rear Axle

Rear Axle

(IF EQUIPPED)

This axle provides added traction on slippery surfaces, particularly when one wheel is on a poor traction surface. Under normal conditions, the limited-slip axle functions like a standard rear axle. The axle may exhibit a slight noise or vibration during tight turns with low vehicle speed. This is normal behavior and indicates the axle is working.

ELECTRONIC LOCKING DIFFERENTIAL (IF EQUIPPED)

Note: The electronic locking differential is for off-road use only and is not for use on dry pavement. Using the electronic locking differential on dry pavement will result in increased tire wear, noise and vibration.

The electronic locking differential is a device housed in the rear axle that allows both rear wheels to turn at the same speed. The electronic locking differential can provide additional traction should your vehicle become stuck. You can activate the differential electronically and shift it on the fly within the differential operating speed range. The differential is for use in mud, rocks, sand, or any off-road condition where you need maximum traction. It is not for use on dry pavement.

The following conditions will affect the electronic locking differential:

The electronic locking differential will not engage if your vehicle speed is above 20 mph (32 km/h) in 4x2, or 4x4 High modes.

The electronic locking differential will not engage if your vehicle speed is above or 56 mph (90 km/h) in 4X4 Low.

The electronic locking differential may not engage if you press your accelerator pedal during an engagement attempt. A message may display in the instrument display guiding you to release the accelerator pedal.

In 4x2, and 4x4 High modes, the electronic locking differential will automatically disengage at speeds above 25 mph (41 km/h) and will automatically reengage at speeds below 20 mph (32 km/h).

In 4L (4X4 low), the electronic locking differential will automatically disengage at speeds above 62 mph (100 km/h) and will automatically reengage at speeds below 56 mph (90 km/h).

The AdvanceTrac system has the ability to take over control of the electronic locking differential and disable it during driving maneuvers when necessary.

When you switch the system on, if you do not meet the required conditions for electronic locking differential activation, the instrument cluster will display the appropriate information guiding you through the proper activation process.

Note: Do not use electronic locking differential on dry, hard surfaced roads. Doing so will produce excessive noise, vibration and increase tire wear.

Note: If the electronic locking differential has difficulty disengaging, release the accelerator pedal and turn the steering wheel in the opposite direction while rolling.

221

E227398

Pull the 4WD control knob toward you.

• The system has malfunctioned and is accompanied by a message in the information display. See your authorized Ford dealer for assistance.

• The vehicle is experiencing an anti-lock brake activation.

On vehicles with an ELD, the size of the spare tire can affect performance of the system. If there is a significant difference between the two rear tires, you may have limited ELD functionality. If the electronic locking differential has difficulty disengaging, release the accelerator pedal and turn the steering wheel in the opposite direction when rolling. We recommend engaging and disengaging the ELD at a stop when you mount a spare on the rear axle.

Turn the control to ON.

Once the indicator light illuminates in the information display, both rear wheel axle

shafts will be locked together providing added traction.

If the indicator does not come on, or the indicator turns off while driving, one of the following has occurred:

• The vehicle speed is too high.

• The left and right rear wheel speed difference is too high during an engagement attempt.

222