Transfer Case: Description and Operation
VTM-4 SystemHow the Circuit Works
The Variable Torque Management 4WD (VTM-4) System distributes driving torque between the front and rear wheels when accelerating. The VTM-4 system also distributes driving torque when any of the wheels lose traction and are slipping.
The VTM-4 control unit controls the current flowing through the electromagnetic coils to engage and disengage the right and left clutches in the rear differential.
When the vehicle is stopped and the transmission is in the R, 2, or 1 positions, the system will fully lock the rear differential clutches when the VTM-4 Lock Switch is pressed.
The major components that make the VTM-4 system work are:
- VTM-4 Control Unit
- VTM-4 Relay
- VTM-4 Lock Switch
- VSA Modulator-Control Unit
- PCM
- Right Side Clutch Electromagnetic Coil
- Left Side Clutch Electromagnetic Coil
Fuse 21 (in the under-dash fuse/relay box) supplies battery voltage to the VTM-4 Control Unit and the VTM-4 Lock Switch when the ignition switch is turned to the ON (II) or START (III) position. When the VTM-4 Lock Switch is closed, a signal is sent to the VTM-4 Control Unit. This signal will indicate the request for VTM-4 lock conditions.
Fuse 4 (in the auxiliary under-hood fuse box) is hot at all times. When the VTM-4 Relay is closed, battery voltage from Fuse 4 is supplied to the VTM-4 Control Unit.