4MATIC Electronic Traction System, Function - GF42.35-S-1000TRA

Model 447 With Transmission 722.965 

Function requirements for electronic traction system 4MATIC, general 

• Drive train operational/engine running
• Electronic Stability Program (ESP®) not deactivated

Electronic traction system 4MATIC, general 

The electronic traction system is a system which operates automatically for improving the starting off and acceleration ability under different road surface conditions. It replaces the automatic locking differential. The system operates via an intervention by the brakes at the driven wheels. The electronic traction system prevents one-sided spinning of the drive wheels when starting off and accelerating as well as the drive wheels spinning briefly on both sides when cornering within specified vehicle speed ranges.

Function sequence for electronic traction system 4MATIC 

Should one or more wheels spin on a smooth surface, the necessary brake pressure is automatically applied at each wheel in order to brake the spinning wheels. Simultaneously, the resulting locking differential effect transfers the drive torque to the wheels that are not spinning. At the same time as the wheel-specific intervention by the brake system, the torque is reduced by the CDI control unit (N3/33) to ensure that the vehicle remains in a controllable driving condition. The ESP® warning lamp symbol in the instrument cluster control unit (A11) indicates when a wheel speed no longer matches the vehicle speed. It warns the driver that he is approaching the physical driving limits with his vehicle.