Dynamic Stability Control Systems - Overview: Overview BMW 7 series E38 facelift

System Overview

The E46 DSC III system consists of the following components

1. Control module/Hydraulic Unit (combined)
2. Four wheel speed sensors
3. Charge pump
4. Tandem Brake Master Cylinder
5. Steering Angle Sensor
6. Yaw Rate Sensor
7. Lateral Acceleration Sensor
8. Two Brake Pressure Sensors
9. Brake Fluid Level Switch
10. DSC Button
11. DSC Warning Indicator
12. CAN Interface (DME/AGS)

DCS Control Overview

The Teves DSC system maintains the lateral location forces during all phases of operation through

1. ABS - Hydraulic intervention preventing the wheels from locking during hard braking
2. ASC +T - Engine drive torque reduction and/or hydraulic intervention on the drive wheels to ensure straight line traction (acceleration - driving and deceleration)
3. DSC - Engine drive torque reduction and/or hydraulic intervention on any wheel brake during cornering to minimize oversteer and understeer conditions

DSC control can aid the driver in controlling the vehicle while driving but can not overcome the laws of physics if the vehicle is being driven beyond the range of DSC control.

Understeer Correction Diagram. Scheme 29

Oversteer Correction Diagrams. Scheme 30

DSC Hydraulic Operation

Based on the programming of the DSC control module, hydraulic intervention can be activated at any wheel brake as follows

1. ABS regulation for any wheel that is in danger of locking, causing the wheel to skid.
2. ASC regulation for either or both rear wheels to ensure that the optimum traction is applied to the drive wheels.
3. DSC regulation for any wheel to correct for dynamic forces that are causing the vehicle to become unstable. The DSC intervention only takes place on one wheel of a corresponding axle.

Depending on the hydraulic intervention required, the charge pump, return pump, changeover valves, charging valves, inlet and outlet solenoids are activated to provide

Identifying Pressure Sensors. Scheme 31

1. Pressure build up for brake application
2. Pressure hold to slow or stop the wheel
3. Pressure release to allow the wheel to turn see scheme 20: DSC Hydraulic Operation Diagram