Electronic Shift Operation

The transfer case (7A195) is equipped with a magnetic clutch, similar to an air conditioning compressor clutch, which is located inside the transfer case adjacent to the lockup collar. The clutch is used to spin up the front drive system from zero to vehicle speed in milliseconds. This spin-up allows the shift between 2-high and 4-high to be made at vehicle speeds listed in the vehicle owner's guide. The spin up engages the front locking hubs. When the transfer case rear and front output shafts reach synchronous speed, the spring-loaded lockup collar mechanically engages the mainshaft hub to the chain drive sprocket and the magnetic clutch is then deactivated. Shifts between 4-high and 4-low can only occur with the transmission safety switches closed. The vehicle's speed must also be within specified limits as determined by the transfer case speed sensor (3 mph or under).

Electronic Shift Control System

This system consists of a two-switch control system, an electronic control module, an electric shift motor with an integral shift position sensor, and a speed sensor.

Switch Control System

There are two control switches located on the upper right corner of the instrument panel for fingertip shift control. The two switches are mounted horizontally and are identified as "4x4" and "LOW RANGE." Two indicator bar lamps are located in the instrument cluster.

When either of the two switches on the instrument panel control are depressed, the first thing that happens is that the electronic control module receives input from the transfer case shift position sensor to verify what position the transfer case is in (2H, 4H or 4L). Next, the electronic control module looks at the speed sensor and the park/neutral position switch or clutch pedal position switch (depending on transmission type). If all conditions are correct to allow the desired shift, the electronic control module will tell the electric shift motor to execute the shift. After the shift has been made and the electric shift motor is off, the control module again looks at the shift position sensor to make sure the proper shift has been accomplished. Finally, the dash indicator light and the push-button light on the control panel will be illuminated by a signal from the electronic control module indicating the desired function has been completed.

Electronic Shift Transfer Case

Item	Part Number	Description
1	7017	Input Shaft
2	7A398	Front Planet
3	7100	High-Low Collar
4	7177	Sprocket, Drive
5	7G361	Electromagnetic Clutch
6	7106	Lockup Sleeve
7	7D126	Lockup Spring
8	7061	Output and Fifth Gear Drive Shaft, Rear
9	7289	Shift Fork, 4WD
10	7219	Lockup Release Spring
11	7G360	Transfer Case Shift Motor
12	7A029	Drive Chain
13	7061	Output and Fifth Gear Drive Shaft, Front
14	3B396	Hub, Auto Locking
15	7N095	Shift Shaft
16	7W074	Range Shift Spring
17	7289	Shift Fork, Range

Electronic Control Module

The electronic control module, located on the passenger side, controls the operation of the transfer case in response to inputs to the push-button control by the vehicle operator, the speed sensor, shift position sensor and the park/neutral position switch.

Speed Sensor

The speed sensor, mounted on the rear of the transfer case, tells the electronic control module the speed of the vehicle to allow range shifts (in or out of 4L) to occur.

Shift Position Sensor

The shift position sensor, an integral part of the electric shift motor, tells the electronic control module the shift position of the transfer case.

Electric Shift Motor

The electric shift motor, mounted externally at the rear of the transfer case, drives a rotary helical cam which moves the 2W-4W shift fork and 4H-4L reduction shift fork to the selected vehicle drive position.