EDL

Electronic Differential Lock
The Electronic Differential Lock (EDL) is a traction control aid for driving away from a standstill. An electronically-controlled brake application at the wheel that is spinning provides a torque reaction point for the differential. This enables the wheel with better traction to make use of the engine power. EDL is effective in both forward and reverse.

EDL is part of the basic configuration of vehicles with All Wheel Drive (AWD). Although EDL only regulates the front wheels on vehicles with Front Wheel Drive (FWD), EDL regulates all four wheels on vehicles with All Wheel Drive (AWD). This makes it possible to eliminate the driver operated mechanical differential lock.

Onset of EDL regulation is permitted up to a speed of 40 km/h. The upper switch-off barrier for already active EDL is 40 km/h for vehicles with Front Wheel Drive (FWD), but 80 km/h for vehicles with All Wheel Drive (AWD).

The hydraulic unit is equipped with suction dampers. They improve pressure build-up in the appropriate brake cylinders during EDL regulation. The functional range of the pressure relief valve in the hydraulic unit is 170 - 25 bar.

To reduce the risk of brake overheating, EDL regulation is not permitted above a specific brake temperature. The temperature limit is defined in the ABS control module (w/EDL) -J104-. The control module determines the actual brake temperature via an algorithm. If the algorithm determines that the brakes have reached a temperature below the temperature limit, the EDL system becomes effective again. Function of the vehicle brake system and ABS are not affected by intervention in this system.

When ignition is switched off, the temperature calculated for the hot brakes is stored until ignition is switched on again. When ignition is switched on, the instrument cluster transmits a time signal so that the ABS control module (w/EDL) -J104- can calculate the standing time. This standing time is required by the temperature algorithm for calculation of the new brake temperature. If the indicated standing time exceeds one hour, the brake temperature is automatically set to the lowest temperature in the temperature algorithm.

EDL shut-off for temperature reasons is indicated in the measuring value block for a period of 20 ignition cycles.