DIFFERENTIAL LOCK

When turning, the vehicle's wheels travel different distances, i.e., they rotate at different speeds.

To compensate for the difference in wheel rotation speed, the drive axle is equipped with a differential.

The Audi Quattro has an additional differential, the so-called center or intermediate differential, located between the front and rear axles, which compensates for the difference in rotation speed between the front and rear wheels.

Differential locks engage when, for example, a wheel of one axle begins to spin on a slippery road surface while the other wheels are on a solid surface and not slipping.

An undesirable difference in wheel rotation speed between the two axles occurs. To prevent and equalize this difference, an additional automatic differential lock is provided, which, in such road conditions, automatically locks the slipping wheel and transfers driving force to the other axle, where the wheels have good traction with the road.

The rear axle differential locking device operates on the same principle.

This lock is primarily intended for smooth vehicle starting from a standstill and for acceleration.

Procedure for Engaging the Rear Axle Differential Lock

The differential locking device is activated by pressing the "DIFF" button located on the center console next to the parking brake lever. It can be engaged or disengaged either before starting to move or while driving at speeds up to 25 km/h.

Pressing the button only engages the device. The lock actually engages only under the appropriate conditions, when a large difference in rear wheel rotation speed occurs.

As soon as the vehicle speed exceeds 25 km/h, the lock disengages automatically.

Also note that if the vehicle speed drops below this value, the system does not engage automatically.

The operation of the differential lock is monitored by the warning lamp located on the panel in front of the "DIFF" button. It illuminates when the differential locking device is actually engaged.

At the same time, the "ABS" warning lamp also illuminates, since the anti-lock braking system (ABS) is disabled when the differential lock engages.

The lamp goes out after the differential lock is disengaged. If this warning lamp does not illuminate when the locking device is engaged, check the electrical system for faults.