BMW 7 Series: New Components

Integrated Chassis Management

The new ICM control unit in the F01/F02 essentially performs the calculations for the control functions that influence the longitudinal and lateral dynamics. The ICM control unit also contains the control functions of "Dynamic Cruise Control" and "Active Cruise Control with Stop&Go function".

In addition, the ICM coordinates the control of the vibration actuator in the steering wheel for the "Lane Departure Warning" and "Lane Change Warning" driver assistance functions. Also integrated into the ICM control unit are micromechanical sensors that supply the driving dynamics signals (in previous vehicles, these were generated by the separate DSC sensor).

Two versions

An ICM control unit is installed in every F01/F02. Which of the two available versions of the ICM control unit is fitted depends on the vehicle's equipment level.

If the vehicle is equipped with one or both of the following options

• Integral Active Steering (IAL) or
• Active Cruise Control with Stop&Go function (ACC Stop&Go),

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 internal layout of the high-end 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).

Fig. 155: Identifying ICM Control Unit (High-End Version) Components

INDEX REFERENCE CHART

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)

Electrical interfaces

The control unit has a 54-pin plug via which the power supply, sensors, actuators and bus systems are connected.

As is the case with the controller housing, the plug does not have a watertight design. This is not necessary as it is installed on the inside of the vehicle.

The ICM control unit is connected to the integrated FlexRay controller via the FlexRay bus system. A detailed description of the new features of the FlexRay network is provided in the Product Information for the F01/F02 bus systems. The communication with most partner control units is handled by the microprocessors in the ICM via the FlexRay.

The FlexRay is routed to the ICM control unit (from the central gateway module) and continues from there (to the DME). The ICM control unit is related to the FlexRay, i. e. not an end node. This is why it does not have a terminating resistor for the FlexRay.

A further bus system, a local CAN , is connected to the ICM control unit in addition to the FlexRay. Its sole purpose is to enable the ICM to communicate with the long-range radar sensor and the short-range radar sensors. This local CAN therefore performs the same tasks as the sensor CAN in the E6x LCI that connects the LDM control unit to the sensors. It transmits information on road users that has been recorded by the sensors.

The local CAN operates in the same way as the PT-CAN with a data transfer rate of 500 kBit/s. There are two terminating resistors for the local CAN, each with 120.. One of these is in the ICM control unit, the second terminating resistor is integrated in the long-range radar sensor. The local CAN is routed to the short-range radar sensors by short stub lines.

The pins for the local CAN are only connected at the plug of the ICM control unit if it is a high-end version.

The ICM control unit is also connected to the wake-up line. The ICM control unit can be woken up via the wake-up line.

Power is supplied from the front fuse carrier by terminal 30B.

Fig. 156: Electrical Interfaces Of ICM Control Unit

INDEX REFERENCE CHART

1. Central gateway module
2. Dynamic Stability Control
3. Short-range radar (SRR) sensor, left
4. Long-range radar sensor (LRR)
5. Short-range radar sensor (SRR), right
6. DME control unit
7. ICM control unit
8. FlexRay routing and continuation without terminating resistor
9. Routing of FlexRay with terminating resistor
10. Routing of local CAN without terminating resistor
11. Routing of local CAN with terminating resistor

W ICM - control unit can be woken up
WUP - Wake-up line

Installation location

The ICM control unit is installed in the center console behind the sensor for the crash safety module. This means that the position of the control unit and its integrated sensor system in the vehicle -near to its center of gravity -is ideal from the point of view of driving dynamics. The mounting points on the body are precisely determined and are measured when the vehicle is manufactured and must not be replaced with any other mounting points.

Fig. 157

INDEX REFERENCE CHART

1. Upper section of housing
2. Mounting bolt
3. Connector
4. Spacer sleeve
5. Lower section of housing

The housing of the control unit is connected to the metal body of the transmission tunnel with four screws and spacer sleeves made of aluminum. The control unit must be mounted on the vehicle body free of play as otherwise vibrations may be induced in the control unit housing which would severely impair the operation of the integrated sensor system. A secondary task of this mounting is to conduct heat away from the control unit to the body.

For the mounting to be able to perform these tasks, the following points must be observed when mounting and replacing the ICM control unit:

NOTE: Only screws and spacer sleeves that are in perfect condition may be used.

A check must then be carried out to make sure the control unit is mounted securely and free of play.

To ensure sufficient heat dissipation and to avoid vibrations, the sides and top of the control unit housing must not come into contact with other vehicle components. Instead, the spaces provided around the control unit as part of the engineering design must always remain free of other components.

Removing and installing the ICM control unit

The ICM control unit performs tasks that are important for many vehicle functions, e. g. provision of sensor signals. If the vehicle were operated without the ICM control unit installed, a large number of vehicle functions would not be available. In the area of dynamic driving systems, for example, the Servotronic and stabilization functions would no longer be available. In addition, fault code memory entries would inevitably also be generated in many control units.

NOTE: If the ICM control unit needs to be replaced, the repair instructions must be observed without fail.

For example, the vehicle battery must be disconnected before removing the control unit and reconnected following the installation. This is the only way to ensure synchronized restarting of the control unit assembly.

NOTE: Once the new ICM control unit has been installed, it must be started up with the assistance of the diagnostic system. To do this, the following steps must be carried out (depending on the equipment specification):

• Calibration of the sensors integrated into the ICM
• Calibration of the ride-height sensors
• Initialization of the Integral Active Steering.

Commissioning the short-range radar sensors

In vehicles with the ACC Stop&Go option, the ICM control unit also plays an important role in the interaction with the short-range radar sensors.

Although short range radar sensors are intelligent sensors that perform the functions of a control unit they cannot be accessed directly via the diagnostic system. The ICM control unit acts as a "go-between" between the short range radar sensors and the diagnostic system which is why the ICM also controls the start-up process for the short range radar sensors.

NOTE: The short range radar sensors for ACC Stop&Go must be started up if one (or both) short range radar sensor(s) is/are replaced. In this instance, the diagnostic system communicates with the ICM control unit. The ICM in turn controls the corresponding functions in the short range radar sensors.

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