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Adaptive Damping System (ADS), Function - GF32.32-P-0002FR

Model 257, 290 up to model year 2021 

with code 459 (Steel suspension with adjustable damping) 

G14549257Courtesy of MERCEDES-BENZ USA

Function requirements in general 

IMPORTANT The electronic ignition lock control unit sends the status of circuit 15 to the adaptive damping system control unit via suspension FlexRay.

Adaptive damping system (ADS), general 

ADS is a continuous damping adjustment system where damping is adapted at each individual wheel. This improves driving safety and driving comfort.

Adjustment of the damping depends on the following factors:

The damping is adjusted harder or softer depending on the driving situation. If the sensor system records a sporty driving style for example, the comfortable basic damping becomes harder automatically. The electronics works continuously within a broadly spread damping performance map. The damping force is adapted to each wheel individually. As a result, the vehicle rolls smoothly even on poor road surfaces, without impairing driving stability.

The ADS function comprises the following subfunctions:

Selection of transmission mode 

Depending in the selected transmission mode, the damping is set correspondingly harder or softer.

By operating the DYNAMIC SELECT switch in the left lower control panel, the driver can select between four preconfigured transmission modes and an individual transmission mode. Depending on the selected transmission program, one of the following settings is activated for the suspension:

For model 257 the following applies: 

The left lower control panel sends the status of the DYNAMIC SELECT switch over the LCP-LIN, Audio/COMAND control panel (except code 446 (Touchpad only)) or touchpad (with code 446 (Touchpad only)), telematics CAN, head unit, user interface CAN, electronic ignition lock control unit and the suspension FlexRay to the Electronic Stability Program control unit.

For model 290 the following applies: 

The left lower control panel sends the status of the DYNAMIC SELECT switch over the Drive Unit CAN, Drive Unit control unit and the suspension FlexRay to the Electronic Stability Program control unit. The Electronic Stability Program control unit then sends the request for the selected transmission mode via the chassis FlexRay to the adaptive damping system control unit.

The adaptive damping system control unit receives the corresponding request and generates the required actuation signals for the actuators. The selected transmission mode is displayed in the instrument cluster. The current transmission mode settings are also briefly shown in the Audio/COMAND display.

The adaptive damping system control unit sends information about the selected transmission mode via the chassis FlexRay, electronic ignition lock control unit and user interface CAN to the head unit and to the instrument cluster. The head unit generates the corresponding image data and sends a switch-on request to the Audio/COMAND display via telematics CAN. The image data is transmitted via the high-speed video link to the Audio/COMAND display.

IMPORTANT After switching on the ignition, the Comfort damping stage is activated.

Recording of driving condition 

The driving condition is defined by the following variables:

The vehicle body acceleration is recorded by the following sensors:

The adaptive damping system control unit reads in the signals from the level sensors directly.

The Electronic Stability Program control unit also transmits information about the wheel speeds, the brake status and the braking torque via chassis FlexRay to the adaptive damping system control unit. This information is used for computation of the vehicle speed and the vehicle body acceleration.

The supplemental restraint system control unit sends information about the turn rate, the lateral acceleration and the longitudinal acceleration via the vehicle dynamics CAN, the Electronic Stability Program control unit and the chassis FlexRay to the adaptive damping system control unit.

The adaptive damping system control unit also receives the following information via chassis FlexRay, which is used to calculate the ideal damping stage or damping force at each shock absorber:

In critical driving situations, the Electronic Stability Program control unit sends the request to switch over the damping stage via the chassis FlexRay to the adaptive damping system control unit.

Damping adjustment 

The adaptive damping system control unit uses the input signals (driving condition) to determine the ideal damping stage in each case and then actuates the following components directly:

The continuous damping adjustment is implemented using single-tube gas-filled shock absorbers. The damping valve units are located at the bottom side on the single-tube gas-filled shock absorbers.

Two proportional valves are installed in each damping valve unit, this enables the compression stage and the rebound stage to be actuated independently of each other.

The flow area in the damping valve unit can be continuously adjusted through actuation of the proportional valves. More or less oil can flow through the damping valve unit to match the set cross section. The damping behavior then becomes correspondingly softer or harder. With activated ESP®, the damping is automatically switched over to the hard damping stage (Sport) in critical driving situations irrespective of the driver's request in order to achieve a more stable driving condition. The hard damping stage remains active for as long as the driving situation requires this.

  Electrical function schematic for adaptive damping system (ADS)   PE32.32-P-2051-97XBA 
  Overview of system components for adaptive damping system (ADS)   GF32.32-P-9997FR 
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