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The development of the running gear is subject to conflicting objectives. For now, besides classic aims such as function, driving safety, strength and durability, requirements such as weight reduction, driving comfort and acoustics are increasingly gaining in importance. At first glance, many requirements appear to be in mutual opposition. A car designed to be very comfortable will lose out in terms of driving safety when driven at the limit. On the other hand, a car with very sporty tuning will achieve considerably higher cornering speeds, and will reach its limit much later. Howeve r, this sporty tuning necessarily entails limi tations when it comes to comfort. In the Audi A8 MY 2003, a newly developed, fully bearing air suspension system is used. In conjunction with the CDC status dependent electronic damping control, this ensures that the main and partly conflicting requirements are satisfied in an optimum manner within the limits of the laws of physics. Contents Page Introduction Basics 4 New technology 4 Operation and display Vehicle levels 6 Operation and display system 9 System components Vehicle overview 10 Control unit J197 12 Suspension/shock absorber strut 13 Shock absorber . 14 Air supply unit 15 Solenoid valve block . 16 Accumulator 16 Pneumatic diagram 18 Pressure build up 19 Pressure reduction 19 Senders sensors . 20 System functions Control concept for standard running gear 26 Control concept for sporty running gear 28 Control concept for special operating conditions . 29 Interfaces System overview of components with bus link CAN, MOST . 34 System overview of components without bus link 35 CAN information exchange . 36 Function diagram . 38 Other interfaces . 40 Service Control unit code 42 System initialisation . 42 Final control diagnosis . 43 Measured value blocks . 43 The home study program informs you about designs and New Caution functions.