System Operation

System Operation:

General Block Diagram:

The following inputs are used to detect dynamic forces acting on the vehicle:

- Vertical acceleration
- Fore and aft acceleration
- Steering wheel angle
- Vehicle road speed
- Condition of road surface




There are three acceleration sensors: one each for the front and rear axles (vertical motion), and one for longitudinal motion. All three sensors are made from the same material and are solid state, piezo ceramic elements. Vehicle movement on the sensors is converted into an electric signal. The control unit uses these inputs to detect road surface condition, vehicle loading and degree of motion. The loading of the vehicle influences vertical motion and is therefore detected by the sensors.

The road speed input comes from the Electronic Body Module (EKM).

The steering angle sensor contains a potentiometer with two wipers which signal the control unit how far and how fast the steering wheel is turned.

The signals received from the sensors are processed by the control unit, which sends signals to solenoids on the front and rear shock absorbers. The system response can be varied by the driver by selecting the Sport (S) or the Comfort (K) position on the console mounted program switch.

Safety Circuit:

The EDC control unit and all components of the system are constantly monitored for malfunctions. Faults which occur in the EDC system are stored in the defect code memory. In addition, defects - depending on type and severity - lead to certain reactions of the control unit (safety circuit) in order to maintain complete driving safety even in the event of serious faults.

Table of Defect Reactions EDC III:

Defect:
Longitudinal acceleration sensor
System reaction:
Acceleration signal is ignored

Defect:
Rear vertical acceleration sensor
System reaction:
Dampers are only operated in the "medium" stage

Defect:
Front vertical acceleration sensor
System reaction:
Dampers are only operated in the "medium" stage

Defect:
Speed sensor
System reaction:
Dampers are only operated in the "medium" stage

Defect:
Steering angle sensor
System reaction:
Dampers are only operated in the "medium" stage

Defect:
"Soft" damper stage electrically defective
System reaction:
Damper stage "soft" replaced by "medium"

Defect:
"Medium" damper stage electrically defective
System reaction:
Damper stage "medium" replaced by "hard"

Defect:
Control unit defective
System reaction:
System is switched off, dampers fixed in "hard" setting