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 depressed, and the transmission must be in NEUTRAL.

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:

- brake ON/OFF switch
- Mode Select Switch (MSS)
- digital Transmission Range (TR) sensor
- 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:

- vehicle speed signal
- mode select switch
Feature 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
- contact plate position inputs A, B, C, D
- vehicle speed signal
- brake ON/OFF switch input (battery voltage when brake is depressed, open circuit when not activated)
- digital transmission range sensor (ground when transmission is in NEUTRAL, open circuit otherwise)

Feature outputs:

- 4WD shift motor outputs
- 4WD LOW cluster indicator (ground when activated, open circuit when deactivated)