Elsewhere on this forum, the TOD was described as being an electrical clutch system utilizing Pulse Width Modulation (PWM) to activate the clutch. All that means is that the vehicle sends longer or shorter pulses to the clutch to adjust the amount of power sent to the wheels.
Your problem could be anything from speed sensors at the wheels, to electrical connection between the computer & the TOD to mechanical problems in the transfer case. That's why we need more detail on what your symptoms are.