Symptom: A BENZW220 (S320) suddenly in the direction of the right front wheel appeared a loud noise, and then immediately lowered the height of the body to the lowest position and can not be driven to the maintenance plant.
    Fault detection: Turn on the ignition switch, then the instrument shows "A-IRMATICVISITWORKSHOP" (maintenance air suspension system). After starting the engine and entering the gear, the instrument displays "AIRMATICSTOPCARTOOLOW" (the air suspension system is faulty and the car is too low). Press the body height control button on the dashboard, the body does not rise. According to the above inspection can be concluded that the car's air suspension system is faulty.
    The car will be lifted, remove the engine under the shield and found that the air suspension system has been damaged air pump, which also fell off the desiccant; check the other parts of the system and found that the front of the two front vibration has been damaged, can not continue to use. Replace the damaged parts, start the engine, hear the sound of the air pump work, while feeling the body in the rise, when the body is raised, the air pump continues to work, while the instrument panel shows "AIRMATICVEHICLERISING" (air suspension system , The body is rising), indicating that the air suspension system is still a problem.
    The car's air suspension system consists of air pump, pressure tank, front and rear pneumatic shock absorber, air distributor, horizontal position sensor and unit. Air pump is not controlled and continuous work may be sustained by the control unit to receive the body caused by elevated signal, the specific reason is that the air pump has a control element or its line fault; Second, the control unit is faulty. Measure the horizontal position of the sensor signal voltage is 2.5V, in the normal range (2.3V ~
    2.7V). Then check the air pump control elements and their lines. In the engine room fuse box to find the air pump control relay, hand the relay to shoot a few times, the air pump actually stopped working. The relay was disassembled and found to be severely ablated. Replace the air pump control relay after troubleshooting.