Control Trac

This feature electronically shifts the vehicle transfer case between 2WD, automatic 4WD, and 4WD LOW. The system mode is selected by the operator through a three-position rotary switch on the instrument panel. The operator is informed which mode the system is in by two cluster indicator lamps, one for a 4WD and one for 4WD LOW. The GEM accomplishes shifts between different system modes by interpreting inputs from the 4x4 selector switch, vehicle speed signal, transfer case rear and front shaft Hall effect speed sensors, and the transfer case contact plates. Based on these inputs, the shifts are controlled through two outputs to the center axle engage and disengage solenoids, two relays (L2H and H2L directional control) to control the transfer case shift motor, and an output for the transfer case electric clutch. While in the automatic four-wheel drive mode, the electric clutch engagement is automatically controlled based on front and rear shaft speed differences (wheel slippage), transferring increased traction to the front wheels. The electric clutch is fully engaged when in the 4WD LOW mode.

A transfer case NEUTRAL capability is also available for vehicle towing needs. This feature will be available and programmed at the dealership. The transfer case can be put in NEUTRAL by placing the transmission in NEUTRAL, the key in the OFF position, and the speed is 0 mph. The transfer case will automatically be shifted out of NEUTRAL if the vehicle ignition switch is moved to RUN or ACCY, or the transmission is moved out of NEUTRAL.