For 1990-2009 cars

The ZF Sachs electronic suspension control system, individually controls the damping force of each of the 4 shock absorbers in order to keep the vehicle’s body as calm as possible. Changes of the damping forces can be accomplished within milliseconds. Suspension characteristics can be changed at any time by activating the sport mode or tour mode.

The electronic suspension control system consists of the following major components:

• | The suspension control module

• | Three body vertical acceleration sensors

• | Two front wheel vertical acceleration sensors

• | Four shock absorber actuators, which are integrated within the shock absorbers

The suspension control module controls the damping forces according to the following factors:

• | Vehicle speed

• | Steering wheel position

• | Engine torque

• | Brake pressure

• | Body and front wheels vertical acceleration

The suspension control module evaluates these inputs in order to separately control the shock absorbers, providing an enhanced ride and comfort level over the widest possible range of operating conditions.

### Suspension Control Module

The suspension control module controls the system functions and detects failures. The suspension control module receives input information by vertical acceleration sensors that are directly connected to the module and by other systems through the serial data line. The suspension control module commands variable levels of current to each shock absorber actuator.

### Vertical Acceleration Sensors

The suspension control module supplies a common 5 V reference and a ground circuit to each of the five vertical acceleration sensor. The vertical acceleration sensors supply a signal of 0.5-4.5 V to the suspension control module.

The three body vertical acceleration sensors are mounted left front, right front and rear. The two front wheel vertical acceleration sensors are mounted at the wheel hub.

### Shock Absorber Actuators

The shock absorber actuators are integrated within the shock absorbers. The electronic suspension control system uses a proportional valve that is located in the external bypass of the displacement unit.

Adjustment is performed by current control. The current consumption is 0-1.8 A. The actuators respond to commands of the suspension control module within milliseconds.

### Driver Information Center Message

The electronic suspension control system does not have a malfunction indicator, but uses the instrument cluster for the display functions instead. When the suspension control module detects a fault that sets a DTC, it sends a message on the serial data line to the instrument cluster, which will display the following message:

SERVICE SUSPENSION SYSTEM

The suspension control module has the ability to store DTCs as current or history codes. Most electronic suspension control system malfunctions will display a message in the instrument cluster and set a DTC. As long as the DTC is present, the message will be displayed.

The suspension control module uses an ignition cycling diagnostic approach. Actions taken when a fault is detected will remain until the ignition is turned OFF, even if the fault condition is not present anymore.

If a fault is no longer present, the DTC will be stored as a history code. After 41 consecutive malfunction-free ignition cycles the DTC will be deleted.