AIRmatic, function - GF32.22-P-0003SX

MODEL 221 with CODE (489) Airmatic (semi-active air suspension) up to Model Year 8

Fig 1: Overview Of AIRmatic Components

Courtesy of MERCEDES-BENZ USA

System overview

Fig 2: Overview Of AIRmatic Electrical / Electronic Components

Courtesy of MERCEDES-BENZ USA

System Overview Electrical / Electronics

Fig 3: Overview Of AIRmatic Components

Courtesy of MERCEDES-BENZ USA

System control algorithm

The control algorithm for this system is also called skyhook algorithm. A deciding criterion for determining the suitable damping force stage (damper adjustment) for the respective driving situation is the direction of motion of the body. For an upwards motion, the damper must provide a hard rebound stage and a soft compression stage. For a downwards motion, a soft rebound stage and a hard compression stage is required.

System functions

The following always applies:

Once the ignition is switched off and switched on again the level last selected as well as the damping stage last adjusted is active.
The information on the damping force stage last adjusted comes from the instrument cluster via the central CAN, from the central gateway control unit (N93), via the chassis CAN to the AIRmatic with ADS control unit.

Wake-up signal

The AIRmatic with ADS control unit is activated (woken up) by the active chassis CAN in order to check the instantaneous vehicle level and to correct it if necessary.

If the AIRmatic with ADS control unit detects a fault the corresponding fault message is led to the central gateway control unit via the chassis CAN and on to the instrument cluster via the central CAN. Thereupon the instrument cluster displays a message in the multifunction display (A1p13).

A level is controlled in wake mode e.g. by loading and unloading the vehicle without the AIRmatic compressor unit cutting in.

A critical condition, such as too low a vehicle level at the front axle, for which the full wheel angle can no longer be guaranteed, is detected by the AIRmatic with ADS control unit as a fault.

If the AIRmatic with ADS control unit detects a fault, the corresponding fault message is transmitted to the central gateway control unit via the chassis CAN and on to the instrument cluster via the central CAN. The driver's attention is brought to the condition by the message "Please wait for a short time, vehicle lifting up". When the active chassis CAN wakes the AIRmatic with ADS control unit a time lead results which is used to correct the vehicle level. The waiting time for level correction is shortened as a result and the availability of the vehicle is increased.

Lifting up from the critical level takes place irrespective of the condition of the on-board electrical system which the vehicle power supply control unit (N82/1) determines. The battery network control unit continuously evaluates the on-board electrical system voltage and interrrupts/prevents the lifting process if necessary. Current-intensive consumers are switched off according to a set sequence until a specified minimum voltage is reached.

	Pressure supply, function		GF32.22-P-4010SX
	AIRmatic suspension, function		GF32.22-P-4011SX