Blind Spot Assist, Function - GF54.71-P-0003LFM
Model 217, 222
as of model year 2018
with code 234 (Blind Spot Monitoring)
Shown on model 217, 222
Function requirements, general
- No undervoltage or overvoltage
- Engine running or drive train operational
- Vehicle moving forward
- Vehicle speed: v ≥ 10 km/h
- No trailer operation (with code 550 (Trailer hitch))
Blind Spot Assist, general
The Blind Spot Assist monitors the rear and side areas of the vehicle using short range radar and, if necessary, informs the driver that an intentional lane change (turn signal active) is not recommended at this time. In a broader sense, Blind Spot Assist serves as an extension of the inside rearview mirror. It does not release the driver of his/her obligation to perform lane changes safely on his/her own responsibility.
The Blind Spot Assist is activated via the head unit. The following options are available for navigating in the control menu:
- With code 448 (Touchpad) navigation can be operated using the Audio/COMAND control panel. The corresponding control signals are sent by the Audio/COMAND control panel (except code 446 (Touchpad only)) over the telematics CAN to the head unit.
- With code 446 (Touchpad only) or code 448 (Touchpad), navigation can be performed using the touchpad. The corresponding control signals are sent by the touchpad (with code 446 (Touchpad only) or code 448 (Touchpad)) over the telematics CAN to the head unit.
- Navigation can be performed by voice control. The driver hands-free system microphone is read directly by the head unit.
- Navigation can be performed via the head unit finger navigation pad and the "Back" button on the steering wheel. The corresponding control signals are sent by the finger navigation pad head unit and the Back button over the steering wheel electronics, steering wheel CAN, steering column tube module control unit, suspension FlexRay, electronic ignition lock control unit and the user interface CAN to the head unit.
- With code 448 (Touchpad) the control menu can be activated with the "CAR" button on the Audio/COMAND control panel. The status of the "CAR" button is sent by the Audio/COMAND control panel over the telematics CAN to the head unit.
With code 446 (Touchpad only) the control menu can be activated using the "CAR" button on the lower control panel. The status of the "CAR" button is sent by the lower control panel over the LCP-LIN, touchpad (with code 446 (Touchpad only)) and the telematics CAN to the head unit.
The head unit sends the status of the Blind Spot Assist via the user interface CAN, electronic ignition lock control unit and periphery CAN to the rear bumper integrated radar sensors.
The visual warning output takes place via the following components:
- Left Blind Spot Assist warning lamp
- Right Blind Spot Assist warning lamp
The acoustic warning is output via the instrument cluster speaker; the readiness indicator is displayed in the instrument cluster. The instrument cluster directly actuates the instrument cluster speaker.
The area which cannot be observed via the outside mirror and inside rear-view mirror is monitored by the following components:
- Right outer rear bumper integrated radar sensor
- Left outer rear bumper integrated radar sensor
All relevant data is evaluated by the integrated rear bumper radar sensors, whereby the right rear bumper radar sensor requests the warning output.
The integrated rear bumper radar sensors operate according to the "Master-slave" principle. The master or slave function can be determined via the connector coding. The master function is defined for the integrated right rear bumper radar sensor. In other words, the integrated left rear bumper radar sensor sends its information via the periphery CAN to the integrated right rear bumper radar sensor which evaluates the corresponding information from both integrated rear bumper radar sensors and sends corresponding requests or data over the periphery CAN to the corresponding control units.
Illustration of the principle of Blind Spot Assist, shown on model 222
The following information is evaluated by the radar sensors integrated in rear bumper:
- Terminal status of terminal 15
- "Blind Spot Assist" status
- Engine running or drive train operational
- Vehicle in forward movement, vehicle speed
- Steering wheel angle
- Trailer operation status (with code 550 (Trailer hitch))
Status of circuit 15:
The electronic ignition lock control unit sends the status of circuit 15 via the periphery CAN to the radar sensors integrated in the rear bumper.
"Blind Spot Assist" status:
The head unit sends the status of the Blind Spot Assist via the user interface CAN, electronic ignition lock control unit and periphery CAN to the rear bumper integrated radar sensors.
Engine running or drive train operational:
The CDI control unit or the ME-SFI control unit sends the "engine running" or "drivetrain operational" signal via the drive train CAN, powertrain control unit, suspension FlexRay, electronic ignition lock control unit and periphery CAN to the rear bumper integrated radar sensors.
Vehicle in forward movement, vehicle speed:
Forward movement is defined via the wheel rotation direction. The vehicle speed is calculated from the wheel speed. The Electronic Stability Program control unit sends this information via the suspension FlexRay, electronic ignition lock control unit and periphery CAN to the rear bumper integrated radar sensors. The rear bumper integrated radar sensors use it to calculate the vehicle speed and the direction of travel.
Steering wheel angle:
The steering wheel angle sensor detects/records the steering wheel angle. The steering column tube module control unit reads in the signals of the steering wheel angle sensor directly and sends information on the steering wheel angle via the suspension FlexRay, electronic ignition lock control unit and periphery CAN to the rear bumper integrated radar sensors.
Trailer recognition (with code 550 (Trailer hitch)):
When the trailer recognition control unit has detected a trailer, it sends the "Trailer detected" status to the integrated rear bumper radar sensors over the interior CAN, electronic ignition lock control unit and periphery CAN.
The Blind Spot Assist system includes the following subfunctions:
- Measuring procedure function sequence
- Function sequence for system and warning messages
Measuring procedure function sequence
Objects (vehicle in blind spot) are detected using the radar measuring procedure. The radar sensors integrated in the rear bumper emit bundled electromagnetic waves as "primary signals". If these waves hit an object, they are reflected by it and are received again by the corresponding radar sensor integrated in the rear bumper as a secondary signal. These signals are used to calculate the distance and the speed of the detected object as well as its angle relative to the vehicle.
The integrated rear bumper radar sensors detection range is based on the angles of the radar waves. These are extrapolated by the respective integrated rear bumper radar sensor to produce the actual monitoring ranges.
Function sequence for system and warning messages
When circuit 15 is switched on, the Blind Spot Assist warning indicators light up in red, until the CDI control unit or the ME-SFI [ME] control unit sends the "Engine running" or "Drive train operational" signal. Additionally, when the "Assistance" menu is switched on in the instrument cluster, the readiness of the Blind Spot Assist is shown in the instrument cluster.
If system errors are detected, a corresponding message is shown in the instrument cluster.
The function readiness status and/or the request to output fault messages is sent by the right rear bumper radar sensor over the periphery CAN, electronic ignition lock control unit and the user interface CAN to the instrument cluster (output of fault messages) and over the periphery CAN, electronic ignition lock control unit and the interior CAN to the respective front door control unit, which then actuates the corresponding Blind Spot Assist warning lamp in each outside mirror.
If at a speed of v ≥ 12 km/h a vehicle is located in the detection range of the radar sensor system, the driver is warned by the Blind Spot Assist warning lamp lighting up red in the outside mirror, on the blind spot side of the vehicle. Predictive warnings of overtaking vehicles are given before they even enter the blind spot, within the framework of the system limitations. If, despite illumination of the Blind Spot Assist warning lamp, the driver still attempts to change lane and indicates this by operating the combination switch (turn signal active), a dual warning tone is additionally output through the instrument cluster speaker when the target vehicle is immediately beside the system vehicle. The Blind Spot Assist warning lamp flashes. If the vehicle leaves the acquisition range of the radar sensor system, the red flashing Blind Spot Assist warning lamp is switched off.
The steering column tube module control unit directly reads in the switch position of the combination switch and sends it to the integrated rear bumper radar sensors over the suspension FlexRay, electronic ignition lock control unit and periphery CAN.
Blind Spot Assist warning lamp, shown on left outside mirror
The following table contains the requirements for displaying system readiness and for showing the visual warning messages:
| Operating state | Blind Spot Assist warning indication in the outside mirror "Off" | Blind Spot Assist readiness indicator in the instrument cluster, function status "On" | Blind Spot Assist readiness indicator in the instrument cluster, function status "Operational" | Blind Spot Assist warning lamp in outside mirror lights up red | Blind Spot Assist warning lamp in outside mirror flashes red |
|---|---|---|---|---|---|
| Circuit 15 OFF | X | ||||
| Terminal 15 ON | X | ||||
| Engine running or drive train operational | X | ||||
| Active Blind Spot Assist activated via the instrument cluster | X | ||||
| Vehicle accelerates, vehicle speed v ≥ 8 km/h | X | X | |||
| Vehicle decelerates, vehicle speed v ≤ 25 km/h | X | X | |||
| Trailer recognized (with code 550 (Trailer hitch)) | X | ||||
| Drive position "R" engaged | X | X | |||
| Vehicle recognized in blind spot | X | X | |||
| Turn signal active, vehicle detected in blind spot | X | X | |||
| Fault detected | X |
Gear range "R" engaged:
Gear range "R" is engaged through the fully integrated transmission control unit. The fully integrated transmission control unit then sends the "Gear range R engaged" status to the electronic ignition lock control unit over the drive train CAN, powertrain control unit and suspension FlexRay. The electronic ignition lock control unit generates a "Reverse gear engaged" status and sends this over the periphery CAN to the integrated rear bumper radar sensors.
| Electrical function schematic, blind spot assistant | PE54.71-P-2051-97SEB | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998LFM |