GF32.22-P-4005TX Level Adjustment, Function

GF32.22-P-4005TX Level adjustment, function
- with CODE (489) Airmatic (semi-active air suspension)

Component Identification:

The AIRmatic at front and rear axle is a fully load-bearing suspension system. It keeps the vehicle level constant when the engine is running irrespective of the load. In the process air is delivered from the AIRmatic compressor unit (A9/1) via the left front suspension strut AIRmatic valve unit (Y51/1), right front suspension strut AIRmatic valve unit (Y52/1), left rear suspension strut AIRmatic valve unit (Y53/1), as well as via the right rear suspension strut AIRmatic valve unit (Y54/1) to the front axle spring struts (40) and rear axle spring struts (41) until the vehicle level has adjusted. The vehicle level recorded by the left front level sensor (B22/8) and right front level sensor (B22/9) at the front axle as well as by the rear axle level sensor (B22/3) at the rear axle and passed on to the AIRmatic with ADS control unit (N51).

An AIRmatic valve is integrated in each front axle spring strut (40) and rear axle spring strut (41)The corresponding level valve and the AIRmatic pressure release valve (A9/1y1) on the AIRmatic compressor unit control the vehicle level

An AIRmatic central reservoir (42) for compressed air also enables the vehicle level to be regulated when the engine is not running. Moreover, the adjustment of vehicle level is decoupled from the AIRmatic compressor unit

Locking function
If the AIRmatic control unit detects that all wheels are unloaded when the vehicle is stationary, the AIRmatic valves are closed. The vehicle therefore remains at the current level. This is essential, for example, when changing a wheel or during repair work (lifting platform).

Normal function (engine runs)
When stationary, the level is re-adjusted after opening a door or luggage compartment lid in the event of a deviation of more than ± 8 mm. When stationary, the level can be compensated every t approx. 5 seconds.

While driving, the level is likewise regulated in the event of a deviation of more than ± 8 mm.

When driving, the level signal is strongly filtered by the AIRmatic control unit due to vehicle vibrations, the level is therefore compensated every t = 180 seconds at the earliest.

Depending on the situation, pressure can be generated by the AIRmatic compressor unit or the pressure supply of the AIRmatic central reservoir (42) can be used to lift up the vehicle. If the vehicle is stationary, pressure from the AIRmatic central reservoir (42) is used for noise reasons. In the event of a particularly high pressure requirement, pressure from the AIRmatic compressor unit and from the AIRmatic central reservoir (42) can also be delivered simultaneously.

When the vehicle is loaded, the lowering of the vehicle level by the level sensors is detected by the control unit. By actuating the solenoid valves, air is delivered to the suspension struts of the front axle (40) or rear axle (41) until the vehicle level has reached its specified value.

When the vehicle is lowered, the level values for the spring struts and, in addition, the AIRmatic pressure release valve are opened, so that air pressure cannot escape into the atmosphere and the vehicle lowers.

Lowering at a standstill
If the vehicle is parked with the active chassis mode "Comfort", all the vehicle doors including trunk lid are closed and the vehicle is locked with the transmitter key (A8/1), the vehicle is automatically lowered by approx. 15 mm into the "Sleep position". If the vehicle is parked with the adjusted level "SportI" it lowers by -10 mm to -15 mm. When the vehicle is parked with the adjusted level "SportII" the level -15 mm is retained.

Function requirements
^ Vehicle stationary
^ Engine Off

If a door is still open after the locking process and if it closed during the run-on time (t = 60 s), as of the condition in which all the doors are locked, the vehicle is nevertheless lowered.

Wake function (function duration approx. t = 1 minute)
With the aid of the transmitter key, the left front door contact switch (S17/3), the right front door contact switch (S17/4), the rear left door contact switch (S17/5) as well as the right rear door contact switch (S17/6) or the trunk lamp switch the AIRmatic control module is "woken up" to check the momentary vehicle level for critical conditions (level too low) and, if applicable, to raise the vehicle or to lower it when unloading.

If the vehicle is lowered more than 20 mm below the level in which it was parked, it is raised by the AIRmatic central reservoir (42) to the normal level (only at reservoir pressure > 11 bar).

At a vehicle level of less than -50 mm on the front axle and less than -60 mm at the rear axle it is even raised from the "critical level" (prerequisite: battery voltage greater than 12.4 V) at a receiver pressure of < 11 bars by the AIRmatic compressor unit.

If the vehicle level deviates by more than ±8 mm from the adjusted level when loading or unloading, it is adjusted to the appropriate level again by pressure reduction or pressure build up in the suspension struts.

It is not possible to raise the vehicle with the level adjustment switch when the engine is shut off.

With lowering when stationary, the vehicle is raised from the sleep position again after starting the engine to the level last adjusted by the driver.

Function in the case of vehicle status "ignition ON"
Same function as for wake-up function, but without time limit.

Run-on function (function duration approx. t = 1 minute)
After "ignition OFF" the AIRmatic with ADS control unit records level changes in order to be able to regulate the vehicle level in the event of any loading or unloading processes (raising or lowering) (the same function as with wake up function).