Transfer Case: Description and Operation

Four Wheel Drive (4WD) Systems

Mechanical Shift

The mechanical shift consists of the following components:

- 4X4 high/low indicator switch
- PCM/4X4 control module
- Integrated wheel ends (IWE) solenoid
- IWEs

The Borg-Warner 44-06 manual shift transfer case is a 3-piece aluminium design. The unit transfers engine power from the transmission to the front and rear axles. Under normal driving conditions, the unit is in two wheel drive high (2H), but when desired, the operator may shift into four wheel drive high (4H) or four wheel drive low (4L). The transfer case is shifted manually. The unit is lubricated by a positive displacement fluid pump that channels fluid flow through holes in the rear output shaft.

Electronic Shift

The electronic shift consists of the following components:

- Mode select switch (MSS)
- PCM/4X4 control module
- Integrated wheel end (IWE) solenoid
- IWEs
- Transfer case shift motor

The Borg-Warner electronic shift transfer case is a 3-piece aluminum design. The unit transfers engine power from the transmission to the front and rear axles. Under normal driving conditions, the unit is in two wheel drive high (2H), but when desired, the operator may shift into four wheel drive high (4H) or 4-wheel drive low (4L). The transfer case is shifted electronically. The unit is lubricated by a positive displacement fluid pump that channels fluid flow through holes in the rear output shaft. The transfer case is equipped with an electromagnetic clutch which is located inside the case. This clutch is used to synchronize the front driveline.


All Wheel Drive (AWD)

The all wheel drive (AWD) consists of the following components:

- Mode select switch (MSS)
- PCM/4X4 control module
- IWEs


The Borg-Warner one-speed torque-on-demand (TOD) transfer case is a 3-piece aluminium design. The transfer case is equipped with an internal electromagnetic clutch. The unit transfers engine power from the transmission to the front and rear axles. Under normal driving conditions, the unit is in all wheel drive (AWD), but when desired, the operator may shift into four wheel drive high (4H). The transfer case is shifted electronically. The IWE's contain an internal spring keeping the front hubs engaged to the front halfshafts at all times. The unit is lubricated by a positive displacement fluid pump that channels fluid flow through holes in the rear output shaft.


Integrated Wheel End (IWE) System

The integrated wheel end (IWE) system contains the following:

^ Vacuum reservoir
^ IWE solenoid
^ IWEs (spring loaded vacuum hubs)
^ Vacuum hoses
^ Check valve

The IWE system uses vacuum hubs that engage the front wheel hubs to the front halfshafts or disengage the front wheel hubs from the front halfshafts.

The IWE solenoid receives engine vacuum from the vacuum reservoir.

When the 4-wheel drive system is in 2H mode, the 4X4 module (PCM) supplies a ground path to the IWE solenoid to apply vacuum to the integrated wheel ends (disengaging the front hubs from the front halfshafts). In 4WD mode, the 4X4 module (PCM) does not supply the ground path to the IWE solenoid, vacuum is not applied to the integrated wheel ends and an internal spring keeps the front hubs engaged to the front halfshafts.