Transfer Case Control Module (TCCM): Notes

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The TCCM controls the operation of the 'on demand' multiplate clutch. The TCCM is located on the underside of the transfer case and is secured with two bolts.

The TCCM receives two power supplies via an AWD relay located in the Engine Junction Box (EJB) for TCCM logic and actuator supply, an ignition supply via the ignition relay in the Central Junction Box (CJB) for system wake-up and a shared ground with the Transmission Control Module (TCM). A high speed CAN (controller area network) bus connection connects the TCCM with the ABS (anti-lock brake system) control module, ECM (engine control module) and other vehicle systems.

The TCCM contains an actuator which is controlled by the TCCM using data from other system modules. The actuator rotates a worm drive which in turn rotates a gear attached to the ball ramp mechanism which applies axial loading to the multiplate clutch. The TCCM controls the torque applied to the front wheels by controlling the axial loading applied to the multiplate clutch in response to information from other system modules. The TCCM can allow a certain amount of 'slip' through the clutch to control the percentage of drive applied to the front driveshaft. If the TCCM targets 100% lock-up of the clutch, the output speed will be equal to the front and rear differentials. The torque distributed depends on the available traction at the wheels which will rotate at the same speed but with different torque, depending on driving conditions. The TCCM can only control the drive to the front driveshaft, the drive to the rear driveshaft is direct from the transmission through the transfer case and is always directly driven.

If the TCCM targets 100% lock-up of the clutch then the speed will be matched between front and rear axles and torque distributed depending on available traction at the wheels same speed, but different torque - depending on driving conditions

The TCCM outputs data on the high speed CAN bus to other system modules to advise the status of the multiplate clutch application.