Electronic Shift Control System Components

MOTOR, ELECTRIC SHIFT
The externally mounted transfer case shift motor, located at the rear of the transfer case, turns the shift cam assembly. As the shift cam assembly sums, it positions the reduction shift fork for desired transfer case operation. An integral position sensor in the shift motor provides motor position information to the Generic Electronic Module (GEM).

SWITCH, ROTARY 4X4 MODE
The rotary 4x4 mode switch, mounted on the instrument panel, allows the operator to select the 4WD Auto, 4WD High, and 4WD Low transfer case operating modes. The indicator light, above the rotary switch dial, will illuminate when the 4WD High or 4WD Low position has engaged.

SWITCH, BRAKE PEDAL POSITION (BPP)
The brake pedal position (BPP) switch is located on the brake pedal. The switch signals the GEM when the operator activates the brake pedal.

SWITCH, CLUTCH PEDAL POSITION (CPP)
The Clutch Pedal Position (CPP) switch is located on the clutch pedal bracket. On vehicles equipped with a manual transmission and an electronic shift transfer case, the clutch pedal must be fully depressed and vehicle stopped in order to make a range shift from HIGH to LOW, or from LOW to HIGH.

SENSOR, DIGITAL TRANSMISSION RANGE (DTR)
The DTR sensor is located on the outside of the transmission near the transmission shift cable attachment. The DTR sensor completes the start circuit in PARK and NEUTRAL, the back-up lamp circuit in REVERSE and the neutral sense circuit (4WD) in NEUTRAL. The DTR sensor also sends a digital output signal to the Powertrain Control Module (PCM) indicating the manual lever position (P,R,N,D,2,1).

SENSOR, THROTTLE POSITION (TP)
The TP sensor is located on the throttle body. The sensor provides throttle position information to the PCM. The PCM converts the throttle position signal to a Pulse Width Modulated (PWM) signal, and sends it to the GEM to control and adjust the transfer case clutch duty cycle.

SENSOR, FRONT AND REAR OUTPUT SHAFT SPEED (OSS)
The externally mounted OSS sensors are located at the rear of the transfer case. The sensors provide the GEM with front and rear driveshaft speeds to control and adjust the transfer case clutch duty cycle.

SENSOR, VEHICLE SPEED SENSOR (VSS)
The Anti-Lock Brake System (ABS) provides the GEM with vehicle speed information to control and adjust the transfer case clutch duty cycle.

GENERIC ELECTRICAL MODULE (GEM)
The GEM controls the operation of the transfer case in response to inputs from the electric shift motor, 4x4 mode switch, CPP switch, BPP switch, DTR sensor, throttle position output from the PCM, front and rear OSS sensors, and the VSS.