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Top Tip Mercedes

Suspension feels hard, and the function for switching off ‘sport mode’ has stopped working.

 
Covers Mercedes W204 / W212 / W207 from 2007 - 2015

Issue

Suspension feels hard, and the function for switching off ‘sport mode’ has stopped working. The red light on the switch is permanently on. (With 7G transmission, only comfort (C) mode is available).
 

Faults

556F00 - The signal values of the level sensors are implausible suspension – ADS

Cause

Incorrect value from suspension level sensor. Check Actual values in ADS control unit - Level Sensors will show voltages between 500 - 4500 mV, and will possibly show that they are within specification at this point. “Vehicle Level” will give a more correct indication of a possible fault. The values for the Front and Rear should be roughly parallel when comparing sides. See attached screen shot for an example of a faulty value. Move the vehicle up/down to confirm the level changes.

Action 

1. Check wiring to sensors. Use the wiring diagram to confirm continuity of suspected level sensor to ADS control unit – (only necessary if open circuit fault detected).
2. Check mountings and security of sensor. If they are OK, replace the sensor.
 
If replacing a level sensor, it is documented that level calibration must be carried out on vehicles with “AIRMATIC”. However, this can only be carried out using specialist measuring equipment (Romess digital inclinometer). Normally if the vehicle is sitting at the correct height, then this process is not normally necessary.