Patent ID: 7553255

Claim:
In a motor vehicle driveline that can transmit power in a 4×4 mode, the driveline having two front wheels, a rear drive shaft, a differential mechanism for transmitting power to two rear axle shafts connected driveably through the differential to the driveshaft, and a clutch for engaging and disengaging a drive connection in the differential mechanism, a method for controlling operation of the clutch comprising the steps of: (a) operating the driveline in 4×4 mode; (b) determining a current speed of each front wheel of the vehicle; (c) determining whether a current speed difference between the front wheels of the vehicle is less than a reference wheel slip for a first predetermined period; (d) determining during a second predetermined period whether a current time rate of speed change of the rear drive shaft is less than a reference rear wheel slip; (e) preventing engagement of the clutch if either of steps (c) and (d) is false; and (f) permitting engagement of the clutch provided steps (c) and (d) are true.