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.
Design of the Two Control Unit Versions: Notes
An ICM control unit is installed in every F01/F02. Each ICM control unit contains the following, irrespective of the equipment installed in the vehicle:
- Two microprocessors
- A FlexRay controller
- Output stages for activating valves in the steering system
- Integrated sensor system for driving dynamics variables (previously: DSC sensor)
The essential tasks of one of the microprocessors are the calculation of control functions, communication processing and activation of the output stages. The main task of the second processor is to monitor safety-relevant functions and bring about a system shut down in the event of a fault.
The other components of the ICM control unit listed above are described in the following chapters.
Two versions of the ICM control unit exist. The version installed in the vehicle depends on the equipment.
If the vehicle is equipped with one or both of the following options
- Integral Active Steering (IAL, SA 2VH) or
- Active Cruise Control with Stop&Go function,
the high-performance version of the ICM control unit is installed.
If neither of these options are installed in the vehicle, the basic version of the ICM control unit is used. The two versions of the ICM control unit are differentiated externally by their part numbers.
The internal layout of the high-performance version differs from the internal layout of the basic version in the following ways:
- Larger microprocessor (required to calculate the Integral Active Steering control and active speed control)
- Redundant sensor system for lateral acceleration and yaw rate (safety requirement for Integral Active Steering).
The following graphics make these differences clear.
| Index | Explanation |
|---|---|
| 1 | Acceleration sensor (longitudinal and lateral acceleration) |
| 2 | Output stages for Servotronic and EVV valves |
| 3 | Controller for FlexRay connection |
| 4 | Two microprocessors (basic version) |
| 5 | Yaw rate sensor |
| Index | Explanation |
|---|---|
| 1 | Acceleration sensors (1 for longitudinal acceleration, 2 for lateral acceleration) |
| 2 | Output stages for Servotronic and EVV valves |
| 3 | Controller for FlexRay connection |
| 4 | Two microprocessors (high-performance version) |
| 5 | Yaw rate sensors (2x) |
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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.