Procedure For Checking The Levelling System

• The vehicle must be standing on a level surface.
• The vehicle must be cold and must not be moved during the check.
• The room temperature should be between 10°C and 30°C and must not fluctuate to any great extent.

1. 1.1 Close vehicle doors.
2. 1.2 Adjust vehicle to terrain level. To do this, tap the rocker switch on the centre console in the appropriate direction until the vehicle is set to terrain level.
3. 1.3 Open the door.
4. 1.4 Select normal level.
5. 1.5 Get out and close the door. The vehicle switches to normal level.

   Do not get back into or out of the vehicle again after setting it to normal level. This can give false alignment results.

6. 1.6 Switch off the levelling system (switch it back on again when work is complete).
   1. 1.6.1 Use > 9818 - PIWIS Tester II to select >> Levelling system/PASM << >> Drive links/checks << >> Activate/deactivate vehicle << in the control unit overview.
   2. 1.6.2 Select the value Deactivate levelling system (permanently) and press F8 to start. The levelling system is now switched off.
7. 1.7 Compress vehicle at front and rear axles by approximately 25 mm 2-3 times and allow it to spring back freely.
8. 1.8 Fit measured-value pickup > VAS 6918 - Quick-Clamping Unit on the relevant wheel.
9. 1.9 Determine the actual value for the height of the vehicle body at the measuring points.

   Courtesy of PORSCHE CARS NORTH AMERICA, INC.

   Dimension X  = upper edge of measured-value pickup to lower edge of wing, shown as an example

   1. 1.9.1 When determining the height of the vehicle body, the height is measured from the lower edge of the wing to the upper edge of the measured-value pickup, dimension X  .
   2. 1.9.2 Then add the radius  of the measured-value pickup 32.5 mm  to this measured dimension X.

   Sample calculation: 

   Measured dimension X = 430 mm; measured-value pickup radius = 32.5 mm

   X + measured-value pickup radius = height of vehicle body 

   430 mm + 32.5 mm = 462.5 mm

10. 1.10 Measure the vehicle height (See  ) again after two hours and compare it with the first measurement. Dimensions and tolerances can be taken from the prescribed vehicle height for vehicles with air suspension.

    > 4495TW ADJUSTMENT VALUES FOR SUSPENSION ALIGNMENT

If the vehicle is lying at an angle, there is a leak at the wheel suspension with the greatest difference between the first and second measurement.

Use commercially available leak detection spray to check the affected air-spring strut/air spring and the relevant air line one after the other.

If there is no difference after two hours, the vehicle height must be measured again after 24 hours.

The following components must also be checked:

• Air line connections
• Air-spring strut/air spring
• Valve unit

If the vibration dampers are faulty, oil from the vibration damper may have entered the air supply system. To ensure that the air spring system works perfectly, it is absolutely essential that you clean the system after a fault is found and replace other components.

• Screw off the affected line on the air-spring strut/air spring and solenoid valve block.
• Blow out the line several times until it is clean using compressed air by introducing the compressed air at the end of the line at the solenoid valve block.
• Check for traces of vibration damper oil in the solenoid valve block.
• If vibration damper oil has contaminated the valve unit, it must be replaced.
• Check the internal line from the compressor to the solenoid valve block.
• If there is oil in the line between the compressor and the pressure accumulator, the line and the pressure accumulator must be replaced.

  If there is oil in the internal line, the compressor must be replaced.