4MATIC Electronic Traction System, Function - GF42.35-P-1000AVI

Model 217, 222 with transmission 725.0 (except 725.096) 

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 drive 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 

If the Electronic Stability Program control unit (N30/4) recognizes one or several spinning wheels through the wheel speed signals, the required brake pressure is built up automatically on the spinning wheel by the traction system hydraulic unit (A7/3) in order to brake the spinning wheels. Simultaneously, the resulting locking differential effect transfers the drive torque to the wheels that are not spinning. To keep the vehicle in a controllable driving condition, along with the wheel-specific interventions by the brake system, the torque is reduced by the ME-SFI control unit (N3/10), which receives the torque reduction signal from the Electronic Stability Program control unit via the suspension FlexRay (Flex E), the electronic ignition lock control unit (N73), the peripherals CAN (CAN PER) and the powertrain control unit (N127). To prevent any downshifting, the ME-SFI [ME] control unit sends the ESP® intervention status to the fully integrated transmission control unit (Y3/8n4) over the drive train CAN (CAN C1).

The Electronic Stability Program warning indicator signals in the instrument cluster (A1) when a wheel speed no longer matches the vehicle speed. To do this, the Electronic Stability Program control unit sends the signal for actuating the Electronic Stability Program warning display via the suspension FlexRay, the electronic ignition lock control unit and the user interface CAN (CAN HMI) to the instrument cluster. The Electronic Stability Program warning indicator then warns the driver that he has approached the physical driving limits with the vehicle.