Differential Assembly: Description and Operation

System Description





This vehicle is equipped with a rear differential system called the variable torque management 4WD (VTM-4) 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.

The operation of the VTM-4 system consists of the following functions: vehicle acceleration torque control (VATC), limited slip differential (LSD), and lock control.

These functions automatically combine to distribute driving torque between the front and rear wheels when the vehicle is being accelerated or when wheels are slipping. When the vehicle is stopped and the transmission is in R, 2, or 1 positions, the system will fully lock the rear differential clutches when the VTM-4 LOCK button is pressed. By design, in lock mode, the torque is reduced gradually 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, a self-diagnosis function, and a provision to communicate with the Honda Diagnostic System (HDS).





^ VATC Control
The torque to be delivered to the rear wheels is calculated based on the acceleration of the vehicle obtained from the PCM.





^ LSD 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 pressing the VTM-4 LOCK button manually when the shift lever is in R, 1, or 2 position.

Electric Control System





VTM-4 Control Unit Electrical Connections

VTM-4 Control Unit Inputs and Outputs
The VTM-4 control unit terminal voltage and measuring conditions for the 4WD control system are shown.





VTM-4 Control Unit Connector Terminal Locations

VTM-4 Control Unit Inputs and Outputs
The VTM-4 control unit terminal voltage and measuring conditions for the 4WD control system are shown.

Part 1:

Part 2:

VTM-4 Control Unit Connector Terminal Locations