New Venture Gear 136 Automatic Transfer Case

WARNING: This page is about a different car, the 2002 GMC Safari and 2002 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.

During normal driving situations the Auto 4WD mode is active. During the Auto 4WD mode the transfer case shift control module monitors rear wheel slip speed (based on the inputs from both the front and rear propshaft speed sensors). When the vehicle experiences a rear wheel slip condition, the transfer case shift control module sends a pulse width modulated (PWM) signal to an electronic motor (transfer case encoder motor). This motor rotates the transfer case sector shaft, applying a clutch pack. This clutch pack is designed to deliver a variable amount of torque (normally delivered to the rear wheels) and transfers it to the front wheels. Torque is then ramped up to the front wheels until the front propshaft speed sensor matches that of the rear propshaft speed sensor. Torque is then ramped down until torque is completely removed from the front wheels or until rear wheel slip is once again detected (the process would then repeat).

View the list of major components that make up the automatic transfer case (ATC) system below.