Four-Wheel Drive Systems
Four-Wheel Drive Systems
The electronic shift on the fly system is an electronically-shifted four wheel drive system that allows the operator to choose between three different modes. The operator can switch between 2WD and 4WD HIGH modes at any speed. To engage or disengage 4WD LOW range, the vehicle speed must be less than 5 km/h (3 mph), the brake pressed, the automatic transmission must be in NEUTRAL. or the clutch must be pressed for manual transmission.
The shift motor sense plate, an integral part of the electric shift motor, informs the four-wheel drive (4WD) control module to the position of the transfer case.
The digital TR sensor is located on the LH side of the automatic transmission; this sensor informs the 4WD control module when the automatic transmission is in the NEUTRAL position.
The electric shift motor is mounted externally at the rear of the transfer case. It drives a rotary cam which moves the mode fork and range fork within the transfer case between the 4WD HIGH, 4WD LOW and 2WD positions.
The 4WD shift motor is controlled by the 4WD control module to shift the transfer case between 4WD HIGH, 4WD LOW and 2WD modes.
System Function
Feature inputs:
- key in RUN or START position
- brake ON/OFF switch
- mode select switch (MSS)
- digital transmission range (TR) sensor (automatic transmission)
- clutch pedal position (CPP) sensor (manual transmission)
- vehicle speed signal transmitted from the powertrain control module (PCM)
- contact plate position inputs A, B. C, D
Feature outputs:
- 4WD LOW indicator (ground when activated, open circuit when deactivated).
- 4WD HIGH indicator (ground when activated, open circuit when deactivated).
- 4WD shift motor outputs.
Shifts between 2WD and 4WD HIGH can be made at any speed. Listed below are the inputs and outputs needed by the 4WD control module to execute a change between any of these modes.
Feature inputs:
- contact plate position inputs A, B. C, D
- mode select switch
Feature outputs:
- 4WD shift motor outputs
- 4WD HIGH cluster indicator (ground when activated, open circuit when deactivated)
When shifting into or out of LOW range, the 4WD control module requires that the vehicle speed is less than 5 km/h (3 mph), the brake is applied, and the transmission is in NEUTRAL.
Feature inputs:
- mode select switch (MSS)
- contact plate position inputs A, B. C, D
- vehicle speed signal
- brake ON/OFF switch input (battery voltage when brake is pressed, open circuit otherwise)
- digital transmission range (TR) sensor (ground when transmission is in NEUTRAL, open circuit otherwise)
- clutch pedal position (CPP) sensor (ground when pressed, open circuit otherwise)
Feature outputs:
- 4WD shift motor outputs
- 4WD LOW cluster indicator (ground when activated, open circuit when deactivated)
Neutral Tow
The neutral tow feature is a program embedded in the 4WD control module, which must be activated by a dealer technician. The neutral tow feature disengages the wheels from the powertrain by shifting the transfer case to the NEUTRAL position. This allows the vehicle to be towed with all four wheels on the ground.
To activate the neutral tow feature, the dealer technician must access the 4WD control module through the diagnostic tool and data link connector. Once communication is achieved, the technician can request the neutral tow feature be enabled. The technician must also install the neutral tow indicator lamp in order for the feature to be activated.
Feature inputs:
- mode select switch (MSS)
- contact plate position inputs A, B. C, D
- vehicle speed signal brake ON/OFF switch input (battery voltage when brake is pressed, open circuit otherwise)
- digital transmission range (TR) sensor (ground when transmission is in NEUTRAL, open circuit otherwise)
- clutch pedal position (CPP) sensor (ground when pressed, open circuit otherwise)
- door ajar switch (battery voltage when door is closed, grounded circuit otherwise)
Feature outputs:
- 4WD shift motor outputs
- neutral tow indicator lamp