Transfer Case-Automatic Four Wheel Drive (A4WD)

Transfer Case

Electronic Shift Control System
Four-wheel drive mode is selected using a rotary switch located on the instrument panel. With the vehicle ignition on, the on-board controller verifies and matches the transfer case shift motor position to the switch.
To shift in and out of 4WD low, three conditions must be met.
^ The automatic transmission must be in NEUTRAL or the manual clutch depressed.
^ The brake must be applied.
^ The vehicle speed must be less than 5 km/h (3 mph).

Electric Shift Motor
The motor assembly and connector, mounted externally on the transfer case cover, drives an electric shift cam which moves the lockup fork and the reduction fork assembly to the selected vehicle drive position. An integral position sensor provides information to the electronic module on the current motor position.

Digital Transmission Range (DTR) Sensor
The DTR sensor is located on the outside of the transmission at the manual lever. The DTR sensor completes the start circuit in PARK and NEUTRAL, the reversing lamp circuit in reverse and the neutral sense circuit (4x4 only) in NEUTRAL. The DTR sensor also sends a digital output signal to the Powertrain Control Module (PCM) indicating the position of the manual lever (P, R, N, D, 2, 1).

Clutch Pedal Position Switch
The clutch pedal position switch is located on the clutch pedal bracket. On vehicles equipped with manual transmissions, the clutch pedal must be fully depressed with the vehicle stopped in order to make a range shift from 4H to 4L, or from 4L to 4H.

Brake Switch
The brake switch is located on the brake pedal. The brake must be depressed in order to make a range shift from 4WD high to 4WD low or back.

Rotary Control Switch
The rotary control switch is located on the instrument panel. The switch consists of a knob with a night time illuminated pointer. The switch is used to select 2WD, 4WD high or 4WD low. The dash indicator light will illuminate when the 4WD high or low position is engaged.

Control Module, Electronic
The electronic control module controls the operation of the transfer case in response to the inputs from the brake switch, the DTR sensor, the clutch interlock switch, and the motor assembly through the actuation of the rotary control switch.

Transfer Case Power Flow
The Borg-Warner 13-54 Shift Transfer Case provides LOW RANGE driving. This system has no selectable neutral.
In the 4x2 mode, torque from the transmission is transferred to the input shaft, which in turn drives the rear output shaft that drives the rear axle assembly.
The 2W-4W shift is accomplished through the shifting of the lockup collar that engages the drive sprocket on the rear output shaft. The drive sprocket turns the drive chain which turns the driven sprocket on the front output shaft assembly. The front output shaft assembly then drives the front driveshaft.
The high-low shift is accomplished when the reduction fork assembly moves the reduction hub to engage the complete carrier assembly to the output shaft. Torque from the input shaft assembly is then transmitted through the sun gear which then turns the complete carrier assembly. The complete carrier assembly, now engaged to the output shaft, provides the reduction.
The unit is lubricated by a gerotor oil pump assembly that channels oil through the bore in the rear output shaft.