Differential Assembly: Description and Operation

Rear Differential System Description

VTM-4 System

Outline

This vehicle is equipped with a rear differential system called the variable torque management(R) 4WD (VTM-4(R)) system. The VTM-4 control unit controls the currents flowing through electromagnetic coils to engage and disengage the right and left clutches in the rear differential assembly.

VTM-4 features include:

- Vehicle acceleration torque control (VATC)
- Limited slip differential (LSD)
- Lock control

Operation

These functions automatically combine to distribute driving torque between the front and rear wheels when the vehicle accelerates or when wheels are slipping. When the vehicle speed is about 18 mph (30 km/h) or below, and the shift lever is in R, 2, or 1, the system will manually engage the rear differential clutches when the VTM-4 LOCK button is pressed. By design, in lock mode, the torque is gradually reduced at speeds above 6 mph (10 km/h) to minimize the load on the 4WD system. The VTM-4 control unit has a fail-safe function and a self-diagnosis function.

VTM-4 System (cont'd)

VATC (Vehicle Acceleration Torque Control)

The torque to be delivered to the rear wheels is calculated based on the acceleration of the vehicle calculated in the VTM-4 control unit.

LSD (Limited Slip Differential) Control

The torque to be delivered to the rear wheels is calculated based on the differences in speed and acceleration between the front and rear wheels.

LOCK Control

Rear differential clutch lock control is done by pushing the VTM-4 LOCK button manually when the shift lever is in R, 1, or 2.

Electric Control System

VTM-4 Control Unit Electrical Connections

VTM-4 Control Unit Inputs and Outputs

The VTM-4 control unit terminal voltages and the measuring conditions for the VTM-4 control system are shown.

Do the VTM-4 inputs and outputs test with the VTM-4 connectors connected.