Related Manuals for Audi 243
Summary of Contents for Audi 243
- Page 1 Service. Pneumatic suspension system Part 2 4-level air suspension in the Audi allroad quattro Design and function Self-study programme 243 For internal use only...
- Page 2 The 4-level air suspension system in the Audi allroad quattro The 4-level air suspension system in the allroad quattro is a logical development of the self- levelling system in the Audi A6. The principles of the suspension/air suspension system and the description of those system components which are identical in the 4-level air suspension system are described in SSP 242.
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Page 3: Table Of Contents
Contents Page System description ....4 Operation and display Operation ................. 7 Display ..................8 Control strategies Control strategies, control unit 4Z7 907 553A ....10 Control strategies, control unit 4Z7 907 553B .... - Page 4 Description of the system The 4-level air suspension system is a fully- The vehicle level is determined separately at supporting level control system with each axle side by means of 4 level sensors. conventional shock absorbers at the front Each air suspension strut is allocated a so- axle and load dependent shock absorbers called air spring valve (transverse check valve) (PDC dampers) on the rear axle.
- Page 5 The 4-level air suspension system is designed One of the special features of the system is as what is known as a pressure accumulator the ability to alter the ground clearance by 66 system. mm in 4 stages. The 4 stages can be controlled manually or automatically (see The pressure accumulator system increases page 7 onwards).
- Page 6 Description of the system The newly developed fully-supporting air • The 4 level stages can be controlled suspension system on all four wheels was manually or automatically within defined designed specifically for the allroad quattro . limits (see page 8 onwards). As well as the advantages of air suspension- based self-levelling, as described for the A6 •...
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Page 7: Operation And Display
Operation and display Operation Pressing the “raise” button once selects the next highest level. By pressing the button repeatedly, it is possible to change, e.g. The self-levelling control unit E281 is used to directly from low level to high level 1. High control the 4-level air suspension and the level 2 cannot be selected until high level 1 display/monitor the system status. -
Page 8: Display
Operation and display Display If the actual level deviates greatly from the The four LEDs which are arranged one on top reference level, this is indicated to the driver of the other in the display zone illuminate with flashing LEDs (according to a level continuously to indicate the current level status. - Page 9 Other button functions Automatic switching Display example: Manual mode and NL The so-called “manual mode” can be switched on or off by pressing the “raise” or “lower” button for at least 3 sec. The yellow LED marked “man” indicates to the driver that the vehicle is in manual mode.
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Page 10: Control Strategies
Control strategies There are two control units currently in use, If the vehicle is at high level 2, it will lower depending on the country. automatically to high level 1 at a speed of > 35 km/h. The system will respond to a The control strategies described below relate request to shift to high level 2 only up to a to the control unit 4Z7 907 553A. - Page 11 Motorway mode The vehicle rises automatically to normal level If the vehicle travels for longer than at the following speeds and time thresholds: 30 seconds at over 120 km/h (vehicle is already at normal level), it will automatically be lowered to low level. Vehicle speed Time This reduces air resistance (saves fuel) and...
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Page 12: Control Strategies, Control Unit 4Z7 907 553B
Control strategies Control unit strategies 4Z7 907 553B The vehicle rises automatically to high level 1 Variations to the description of control unit 4Z7 907 553A are outlined below: at the following speeds and time thresholds: • No parking level control Vehicle speed Time •... -
Page 13: Esp Safety Switching
Normal ESP functions are available again and the ESP warning lamp extinguishes. In the Audi allroad quattro it is possible to This ESP safety switching takes place as of influence certain ESP functions using the ESP 70 km/h at high level 2 and as of 120 km/h at button. -
Page 14: System Components
Air connection coaxially with the dampers as a suspension strut. The rear air springs are identical in design and function to those of the Audi A6 with self-levelling. Design While in the case of the rear suspension strut, the connection/seal from the air spring (piston) to the... - Page 15 Rear suspension strut The bayonet connection must be absolutely clean and is greased with a special lubricant before installation (see Workshop Manual). O-ring For installation, the air spring is pushed on Locking cap and then turned. Operating pressure of the air springs front rear Minimum...
- Page 16 System components Warning: Air springs must not be moved when pressureless because the air bellows The piston must not be touched during cannot unroll on the piston and would installation or transport of the be damaged. complete suspension strut assembly as In a vehicle with depressurised air the piston can be easily pushed back springs, the relevant air springs must...
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Page 17: Air Suspension
flow noise, particularly during discharge. the differences in the 4-level air suspension • Temperature monitoring is performed via system in the Audi allroad quattro a temperature sensor at the cylinder head and a simulation formula in the control • The fitting location is outside the vehicle... - Page 18 System components In normal operation the compressor is allowed to run only when the engine is running. Exceptions: Damping element – Final control diagnosis – Basic system setting – In pre-run upon recognition of an extremely low level Spiral spring A special mounting consisting of spiral springs and rubber damping elements prevents the transfer of vibrations to the...
- Page 19 Pressure accumulator Air supply strategy The pressure accumulator allows the vehicle At driving speeds of < 36 km/h air supply is level to be raised more rapidly with minimal effected primarily by the pressure noise as the pressure accumulator is only accumulator (provided sufficient pressure is filled while the vehicle is in driving operation available).
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Page 20: Diagram Of Pneumatic System
System components Pneumatic diagram Additional noise damper Valve for pressure accumulator N311 Non-return valve 1 Valve for FL suspension strut N148 Valve for FR suspension strut N149 Air dryer Valve for RL suspension strut N150 Non-return valve 3 Valve for RR suspension strut N151 Non-return valve 2 Pressure accumulator Discharge throttle... -
Page 21: Solenoid Valves
Solenoid valves The 4-level air suspension has 6 electric The 4 air spring valves N148, N149, N150, solenoid valves. N151 and accumulator valve N311 are combined in one valve unit. They are designed as 2/2 way valves and are closed Discharge valve N111 forms a functional unit together with the pneumatic discharge valve without current. -
Page 22: Temperature Sensor G290
System components Temperature sensor G290 Temperature sensor G290 (Overheat protection) To enhance system availability, temperature sensor G290 is attached to the cylinder head of the compressor. A temperature model is implemented in control unit J197 which prevents overheating of the compressor while simultaneously utilising the maximum possible raising times. -
Page 23: Level Senders G76, G77, G78, G289
PWM signal proportional to the angle (for 4-level air suspension). The angle sensor used in the Audi allroad quattro is a contact-free sensor which operates according to the induction principle. A special feature of the level sensor used is that it produces two different output signals proportional to the angle. - Page 24 System components For technical reasons, the voltage for the left- Pin assignment for the level sensor hand level sensors (front left G78 and rear left G76) is supplied by the headlamp range control unit J431. Power is supplied to the Earth right-hand level sensors (front right G289 and (left from J431, right from J197)
- Page 25 Construction/design The rotor consists of a closed conductor loop The angle sensor consists essentially of the connected to the sender arm (rotates with the stator and the rotor. sender arm). The conductor loop has the same geometric shape as the receiver coils. The stator consists of a multilayer circuit board comprising the exciter coil, three receiver coils and the control/evaluation...
- Page 26 System components Function Exciter coil 3 receiver coils The exciter coil is subjected to an alternating current which produces an electromagnetic alternating field, the induction of which is penetrated by the rotor. The current induced in the rotor produces a Stator second electromagnetic alternating field around the conductor loop (rotor).
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Page 27: Warning Lamp K134
Level sensors, summary The advantages of the angle sensor are the As no magnetic materials are required, proportional measurement process along temperature and age cause only minimal with their contact-free and therefore wear- variances in the measured values. Such free operation. variances are caused by a reduction in the strength of the magnetic field of permanent The generation of ratios (proportional... -
Page 28: Operating Unit E281
System components Operating unit for self- levelling E281 The operation and displays of the operating Control unit J197 transmits the information unit are described on page 7. In this section, concerning the vehicle level and the system the function of the operating unit will be status back to the E281 via the K wire, described. -
Page 29: Interfaces
Interfaces CAN information exchange In the case 4-level air suspension, the information exchange between control unit The system overview shows the information J197 for the self-levelling system and the provided by the gearbox control unit via the networked control units is performed via the CAN bus which is received and used by the CAN drive with the exception of a few networked control units. -
Page 30: Additional Interfaces
Interfaces Additional interfaces The door contact signal … The driving speed signal … ... is an earth signal from the control unit for ... is a square-wave signal produced by the central locking. It indicates that the door or dash panel, the frequency of which is boot lid/tailgate is open. - Page 31 to the self-levelling suspension The trailer operation signal … control unit J197 (pin 2/10) ..comes from the F216 contact switch in the from the rear fog light trailer socket. switch When the plug is connected, contact switch F216 connects control unit J197 to earth. See also “Trailer operation”.
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Page 32: Function Diagram
Interfaces Functional diagram Terminal 15 Terminal 30 Terminal 30 J403 N148 N150 N149 N151 G291 N311 T.34 N111 t° G290 243_038 J197 F216 G289 E281 J431... - Page 33 Key to function diagram E281 Self-levelling suspension operating = Input signal unit = Output signal F216 Contact switch for switchable rear fog light = Positive Self levelling suspension sender, RL = Earth Self levelling suspension sender, RR Self levelling sender, FL = Bi-directional G289 Self levelling suspension sender, FR...
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Page 34: Control Concepts
Control concepts The system can be tested via the self- Self-levelling suspension diagnosis or test adapter 1598/35. control unit J197 For further information, see “Service” chapter. The central element of the system is the control unit which, in addition to its control Address word 34 functions, enables the monitoring and diagnosis of the entire system. -
Page 35: Modes
Modes Height mode/driving mode Reaction times upon level deviation Driving speed Reaction time <5 km/h approx. 5 seconds Height mode approx. 1 second at extremely low level >10 km/h approx. 50 seconds or Driving mode 15 minutes depending on the level deviation Control characteristics during level change Level change process:... - Page 36 Control concepts Sleep mode The system can switch between sleep mode To minimise electricity consumption the and run-on/run-up mode, triggered via the control unit switches to “system idle” (sleep door contact signal, a maximum of 15 times. mode) after 15 minutes. For the 15 subsequent wake-up procedures, the system switches to sleep mode after only There is no level adjustment in sleep mode.
- Page 37 Trailer operation The correct position of the tow bar on the trailer attachment during trailer operation is indicated in normal mode. Contact switch F216 in the 13 pin trailer socket is used to signal that the trailer plug is inserted, i.e. indicates trailer operation (see description “Trailer operation signal”.
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Page 38: Service
Service Special tools Due to the limited number of Adapter cable 1598/35 with test box 1598/14 connections to test box V.A.G. 1598/14, are used for fault finding and function testing not all interfaces in control unit J197 of sensors and signals of the 4-level air are wired. -
Page 39: Basic System Settings
Basic system setting The basic system setting of the reference Codes for the allroad quattro level in the 4-level air suspension system is 25500 performed by inputting body-level measured values at normal level. Position Meaning The measured value, the vertical dimension X0000 1 = Headlamp control not from the wheel centre to the wheel cut-out,... -
Page 40: Self-Diagnosis
Service Self-diagnosis Address word: 34 Self levelling suspension Both generations of diagnostic tester (V.A.G. 1551/1552 and VAS 5051) are suitable for communication with the 4-level air suspension control unit. Due to the limited capacity of the tester program cards, there are display text limitations in the case of diagnostic testers V.A.G. -
Page 41: General Overview
General overview Allroad quattro control strategies 4-level air suspension + additional shift stage Control unit 4Z7 907 553A/B... - Page 42 Notes...
- Page 44 All rights reserved, including the right to make technical changes. AUDI AG Dept. I/VK-5 D-85045 Ingolstadt Fax 0841/89-36367 040.2810.62.20 Technical status 11/00 Printed in Germany...