BMW 7 Series: System Components

Vehicle-specific Modifications in Detail

Long-range Radar Sensor

In terms of physical design, the long-range radar sensor (LRR) for ACC Stop&Go in the F01/F02 is largely identical to the one fitted in the E6x LCI.

Functionally, however, it differs from the sensor in the E6x LCI in that it also calculates the new collision warning of the Adaptive Brake Assistant.

In the F01/F02, the long-range radar sensor no longer has a connection to the wake-up line. Instead, it is supplied with power by terminal 15N and is thus hard switched. Terminal 15N is tapped off at the front fuse carrier. The long-range radar sensor contains a terminating resistor (for the local CAN) as it does in the E6x LCI.

The installation location of the long-range radar sensor and the way it is mounted have been adapted to the structural conditions specific to the F01/F02.

Fig. 153: Installation Location Of Long-Range Radar Sensor In F01/F02

INDEX REFERENCE CHART

1. Fixed bearing
2. Connector
3. Screw for horizontal adjustment
4. Housing/radome
5. Screw for vertical adjustment
6. Bracket

NOTE: In the F01/F02, the long-range radar sensor is fitted with the connector at the top. It should therefore be noted that the adjustment screws have had to be relocated.

NOTE: Adjusting the long-range radar sensor on vehicles with Integral Active Steering: Before the adjustment device is set up and the actual adjustment work can begin, it is necessary to bring the actuator for the rear-wheel steering to the straight-ahead position. It is essential that the instructions of the diagnostic system and Repair Instructions be observed.

Short-range radar sensors

The short-range radar sensors (SRR) used for ACC Stop&Go in the E6x LCI have undergone a hardware revision. New, integrated switch circuits have been implemented. The principle of operation, however, is much the same. The table below compares the sensors' properties with those of the Lane Change Warning.

SHORT RANGE RADAR SENSOR/LANE CHANGE WARNING SYSTEM COMPARISON CHART

NOTE: As in the E6x LCI, the short-range radar sensors cannot be programmed. While they do have a self-diagnostics function, accessing the ICM control unit is the only means by which it is possible to read their fault code memory entries.

The short-range radar sensors on the left and right are identical, as they are in the E6x LCI. Each of the short-range radar sensors detects its respective installation position from the pin that is assigned to ground in the wiring harness.

In the F01/F02, the short-range radar sensors -like the long-range radar sensor - are supplied with power by terminal 15N, which is supplied in turn by the front fuse carrier. There is no connection to the wake-up line.

The local CAN is connected to the short-range radar sensors by two short stub lines, which begin at the long-range radar sensor.

The short-range radar sensors have no terminating resistor for the local CAN.

The F01/F02 and the E6x LCI differ greatly in the installation location of the short-range radar sensors and in the way they are mounted. The key differences are illustrated here using as an example a short-range radar sensor fitted on the right-hand side when viewed in the direction of travel.

Fig. 154: Identifying Housing/Antenna Cover, Bracket And Connector

INDEX REFERENCE CHART

1. Bracket
2. Connector
3. Housing/antenna cover

In the F01/F02, the short-range radar sensors are fitted on top of the bumper carrier (and no longer on its front).

For this reason, the bracket had to be completely redesigned. It now grips the housing of the short-range radar sensor from behind. To guarantee the necessary level of stability and reliability, the bracket now also has a reinforcement rib. This runs vertically to the front of the antenna cover. The rib was positioned here in order to minimize its interference with the propagation of radar waves.

NOTE: The material for the bracket (and thus for the rib) was also selected specifically for this particular application. Emergency repairs that use other plastic parts are not permitted. Otherwise, there is a risk that the short-range radar sensors may not work correctly.

For the short-range radar sensors, a distinction is made between the following types of fault:

• Sensors dirty: The short-range radar sensors can no longer function reliably if their antenna is covered by snow, slush or ice. If this condition is detected, a corresponding signal is sent to the ICM control unit.

  The ACC Stop&Go function is deactivated as a result. A separate Check Control message informs the driver about this special case. There is no fault code memory entry.

• External interference with radar signal processing: Radar sensors used by other vehicle manufacturers may interfere with the signal evaluation of the short-range radar sensors. If such a problem is detected, the ACC Stop&Go is deactivated. It can be switched on again by the driver as soon as the vehicle is far enough away from the vehicle causing the interference. This malfunction is logged in the fault code memory of the ICM control unit. However, there is no repair action that can be taken. Instead, the customer should be informed of the cause of the fault (external interference).
• Temporary fault: The causes of this type of fault include communication faults, overvoltage, undervoltage and thermal overloads in the short-range radar sensors. In these cases, it is necessary to proceed as instructed by the test plan in the diagnostic system. The short-range radar sensors must not be replaced unless the test plan prompts you to do so.
• Control unit fault: If one of the short-range radar sensors is affected by a control unit fault, the only way to rectify the fault is to replace the defective sensor.
• Sensors maladjusted: As with the long-range radar sensor, the short-range radar sensors in interaction with the ICM control unit are also able to detect a maladjustment caused by an accident. If the calculated degree of maladjustment exceeds a certain limit, the ACC Stop&Go function is shut down. An entry in the fault memory indicates the cause of the fault. To correct the fault, observe the instructions in the diagnostic system and Repair Instructions.

In the F01/F02, too, as with the long-range radar sensor, there is no means of adjusting the short-range radar sensors.

NOTE: If a short-range radar sensor has been replaced with a new one, it is necessary to commission the sensor using the diagnostic system. While commissioning is in progress, new short-range radar sensors are taught their respective installation position and, importantly, their angle relative to the vehicle longitudinal axis. A measurement does not need to be carried out in this case.

The angle entered is the angle predetermined by the construction and the form of the bumper support.

NOTE: Great care must taken during repair work carried out at the front end. If the bumper carrier is deformed or if the bumper trim is scratched or dented, the short-range radar sensors may no longer work correctly. The specified structural clearances between the short-range radar sensors and the bumper trim must also be maintained. The Repair Instructions must be observed without fail.

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