Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Interface with ICM control unit
As shown in the system circuit diagram, each ride-height sensor (irrespective of the version) is connected to the ICM control unit by three lines. The double-type ride-height sensors at the rear axle are also connected to the EHC control unit according to the same principle via three additional lines.
Power is supplied by the ICM control unit to the ride-height sensor via one of the lines. The sensor uses the second line to deliver its measurement signal (0-5 V DC voltage). The third line is connected to a common ground inside the ICM control unit.
The measurement signal is evaluated by means of voltage measurement in the ICM control unit. The ICM control unit cannot calculate the actual ride-level heights in millimeters on the basis of this information alone. To perform this calculation, the ICM control unit must be able to map the voltage signals it receives to reference values. This is the only way to establish a relationship between the measurement signals and the actual ride-level heights. These reference values are determined during a synchronization procedure.
- following replacement of the ICM control unit,
- following replacement of a ride-height sensor or
- if prompted to do so by the test schedule of the diagnostic system (due to a fault code memory entry in the ICM).
The synchronization does not have to be carried out if a wheel has been changed.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.