Transfer Case: Description and Operation
VTM-4 SystemHow the Circuit Works (4WD)
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 loses traction and is 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:
- Left Side Clutch Electromagnetic Coil
PCM
- Right Side Clutch Electromagnetic Coil
VSA Modulator-Control Unit
- VTM-4 Control Unit
- VTM-4 Relay
- VTM-4 Lock Switch
Fuse 11 (in the driver's under-dash fuse/relay box) supplies battery voltage to the VTM-4 Control Unit when the ignition switch is turned to the ON (II) position.
Fuse 9 (in the driver's under-dash fuse/relay box) supplies battery voltage to the VTM-4 Control Unit through the VTM-4 Lock Switch when the ignition switch is turned to the ON (II) or START (III) position. The VTM-4 Lock Switch must be closed for the voltage to reach the VTM-4 Control Unit. This signal will indicate the request for VTM-4 lock conditions.
Fuse 4 (in the auxiliary 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.