demand from the driver si to the abs esp unit 2 and it may also receive information from the abs esp unit 2 e g in the form of a torque request t engreq the abs esp unit 2 may send signal s s 2 to an all wheel drive coupling 4 such as a limited slip coupling lsc or a clutch if e g cornering is demanded and it may receive signal s from the all wheel drive coupling 4 about a transferred torque t ls c the abs esp unit 2 can also provide a braking torque for a rear inner wheel r u03b2rbr i nner the normal communication between the engine management system 3 and the all wheel drive coupling 4 is represented by s 3 the all wheel drive coupling 4 can also send a signal directly to the engine management system 3 and this is denoted as s 4 in fig1 a vehicle 100 provided with an all wheel drive system can be seen in fig2 the vehicle 100 is equipped with an engine 101 a transmission 102 for transferring a motive torque from the engine to a primary drive shaft 103 u2032 a secondary drive shaft 103 u2033 a front 104 and a rear 105 differential and an all wheel drive coupling 4 106 transferring torque from the primary 103 u2032 to the secondary drive shaft 103 u2033 or vice versa under certain circumstances the differentials 104.