BMW SERVICE TRAINING - Air suspension lever control system (Seminar Working Material)

Air Suspension Level Control System

History

- General

The function of the level control system is to maintain the height of the vehicle body as closely as possible at a prespecified level under all load conditions.

Thanks to the extensively constant level, the geometric wheel suspension data (e.g. wheel camber, toe-in) remain unaltered by the load. The ride comfort is also not dependent on the load.

The headlight range remains extensively constant over the entire load.

BMW previously supplied level control systems as both special equipment and, in part, as standard equipment on the BMW 7 Series - E23/E32, 6 Series - E24 and 5 Series -E12/E28.

Hydropneumatic suspension

Partially loaded hydropneumatic rear-axle suspension forms the basis of these systems.It is similar in its basic principle to pure air suspension. However it operates with a volume of gas which is permanently contained in the pressure accumulator (i.e. constant).

The gas used is nitrogen. The internal chamber of the pressure accumulator is divided by a diaphragm into individual gas and hydraulic fluid chambers

CHAP 1 Air Suspension Level Control System 1

History 1

- General 1

Introduction to air suspension 5

- General 5

Pneumatics diagram 7

- Single-axle air suspension 7

- Twin-axle air suspension 8

System overviews 9

- E39 electrical system schematic high (MY 2002) 9

- E65/E66 electrical system schematic (MY 2002) 10

- E53 electrical system schematic high (MY 2002) 11

Air suspension components 12

- Graphical system overview 12

- Air supply unit (LVA) 14

- Control unit (EHC) 15

- Air suspension 16

- Ride height sensor 21

- Pressure accumulator valve unit 22

- Check Control messages 23

- Control button 25

Air suspension function 26

- Model overview table 26

- Control mode flow charts 27

- Control mode overview table 30

- Faults 32

- Explanation of terms 32

- Control modes 35

Operating principle

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