Blind Spot Assist, function - GF54.71-P-0003GV
MODEL 164.1/8, 251.0/1 as of model year 2011 with CODE 234 (Blind Spot Monitoring)
Blind Spot Assist function requirements, general
- No undervoltage or overvoltage
- Function "Blind Spot Assist" in "Assistance" menu activated in instrument cluster
- Radar sensor system not shut off (model 251 up to 31.5.13, model 164)
- Engine running or drive train operational
- Vehicle moving forward
- Gear range "D" engaged
- Vehicle speed v ≥ 30 to 250 km/h
- No driving with a trailer (with code (550) Trailer hitch or code (553) Mechanically folding trailer hitch)
Blind Spot Assist, general
The Blind Spot Assist monitors the rear and side area of the vehicle using short range radar and, if necessary, informs the driver that an intentional lane change (turn signal set) is not recommended at a given point in time. In the broader sense, the Blind Spot Assist system acts as an extension of the rear-view mirrors. It does not release the driver of his/her obligation to perform lane changes safely on his/her own responsibility.
In the left electrically adjustable and heated outside mirror and the right electrically adjustable and heated outside mirror, a visual indicator signals the status of the Blind Spot Assist and warns of critical situations when changing lanes (i.e. a vehicle is in the blind spot). In addition, an acoustic warning can also be given.
The visual warning output takes place via the following components:
- Left Blind Spot Assist readiness and warning indicator
- Right Blind Spot Assist readiness and warning indicator
The acoustic warning is output via the warning buzzer in the instrument cluster.
The area which cannot be observed via the outside mirror and inside rearview mirror is monitored by the following components:
- Left rear bumper intelligent radar sensor
- Right rear bumper intelligent radar sensor
All relevant data are evaluated by the rear bumper radar sensors, whereby the right rear bumper radar sensor requests the warning output.
The 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 right rear bumper radar sensor. In other words, the left rear bumper radar sensor sends its information via engine compartment CAN to the right rear bumper radar sensor which then evaluates the corresponding information from both rear bumper radar sensors and sends corresponding requests or data via engine compartment CAN to the corresponding control units.
The following information is evaluated by the Blind Spot Assist:
- Terminal status of terminal 15
- "Blind Spot Assist" function status (function requirement)
- Engine running or drivetrain operational (function requirement)
- Vehicle in forward movement, vehicle speed (function requirement)
- Gear range "D" engaged (function requirement)
- Trailer recognition (with code (550) Trailer hitch or code (553) Mechanically folding trailer hitch) (function requirement)
Status of circuit 15:
The EZS control unit transmits the status of circuit 15 to the rear bumper radar sensors via engine compartment CAN. Status of "Blind Spot Assist" status:
The instrument cluster sends the status of the "Blind Spot Assist" function to the rear bumper radar sensors via engine compartment CAN.
Engine running or drivetrain operational
The CDI control unit or the ME-SFI control unit transmits the signal "Engine running" or "Drivetrain operational" to the rear bumper radar sensors via engine compartment CAN.
Vehicle in forward movement, vehicle speed:
Forward movement is defined via the wheel rotation direction. The vehicle speed is calculated on the basis of the wheel speeds.
The ESP control unit (except model 164.195) or the regenerative braking system control unit (on model 164.195) transmits the information about wheel rotation directions and wheel speed to the rear bumper radar sensors via engine compartment CAN.
Gear range "D" engaged:
The fully integrated transmission control unit (VGS) (except model 164.195) sends information about the engaged gear range to the rear bumper radar sensors via engine compartment CAN.
On model 164.195, the hybrid fully integrated transmission control controller unit transmits information about the engaged gear range to the rear bumper radar sensors via hybrid CAN, ME-SFI control unit and engine compartment CAN.
Trailer recognition (with code (550) Trailer hitch or code (553)
Mechanically folding trailer hitch):
The rear SAM control unit sends information on the trailer recognition via interior CAN, central gateway control unit and engine compartment CAN to the rear bumper radar sensors.
The Blind Spot Assist system includes the following subfunctions:
- Measuring procedure function sequence
- System and warning messages function sequence
Measuring procedure function sequence
The vehicles are recorded based on the radar measuring method. The rear bumper radar sensors with pooled electromagnetic waves as so-called primary signals. If these meet a vehicle, they are reflected by it and received again by the corresponding rear bumper radar sensor as secondary signals. These signals are used to calculate the distance and the speed of the detected object as well as its angle relative to the vehicle.
Detection area of the radar sensor system
Automatic shutoff of radar sensor system (model 251 up to 31.5.13, model 164):
Due to legal requirements on the 24 GHz radar system (short range radar) in Western Europe, the radar sensor system is automatically deactivated in certain protected areas around radio astronomy stations. In other words the Blind Spot Assist is not functional in these ranges. The restricted areas around radio astronomy stations are stored in the rear bumper radar sensors.
The radio and navigation unit (with code (511) Audio 50 APS with DVD changer or code (525) MB Audio 50 APS radio) or the COMAND operating, display and controller unit (with code (512) COMAND APS with DVD changer or code (527) COMAND APS with single DVD drive (with navigation)) sends location information from the navigation system via interior CAN, central gateway control unit and engine compartment CAN to the rear bumper radar sensors.
When the Blind Spot Assist is active, the message "Radar sensor system automatically switched off, see operating instructions" is displayed in the multifunction display of the instrument cluster. The Blind Spot Assist readiness and warning indicators light up in yellow.
Detailed information about the signal path for output of the message in the multifunction display of the instrument cluster can be found in the chapter "Function sequence for system and warning messages".
If the vehicle is parked in a restricted area, then when it is started up again the GPS coordinates are used for position finding. The driver is notified again that the radar sensor system was automatically switched off. If the vehicle leaves the restricted area, the radar sensor system is automatically switched on again. The "radar sensor system automatically switched off, see operator's manual" message is canceled and the yellow Blind Spot Assist readiness and warning indicator lamps are switched off.
Manual switching on/off of the radar sensor system:
There is also the possibility of switching the radar sensor system off and on again manually via the "Vehicle" menu in the instrument cluster. If the radar sensor system was automatically switched off within a restricted area, the manual switch-on option is no longer available and the following message is shown "Radar sensor system automatically switched off, see operator's manual". The request for switching the radar sensor system on and off is sent by the instrument cluster to the rear bumper radar sensors via engine compartment CAN.
On model 251 as of 1.6.13, the radar sensor system is no longer automatically switched off. Use of the reduced frequency band range from f = 24.25 GHz to 25.65 GHz means that this is no longer necessary. Both the NATO band and the radio astronomy band are blanked out. Operation of the radar sensor system within the restricted areas of the radio astronomy stations is thereby rendered possible.
Localization of the vehicle via global positioning system (GPS) is therefore also no longer necessary.
System and warning messages function sequence
When circuit 15 is switched on, the Blind Spot Assist readiness and warning indicators are switched on for t = 1.5 s turning first red then yellow. When a speed of v > 30 km/h is reached the Blind Spot Assist readiness and warning indicators are switched off and the Blind Spot Assist is ready for warning.
If a system fault is found, a corresponding message appears in the multifunction display and the readiness and warning indicators for the Blind Spot Assist light up yellow.
The status of the system readiness or the request for output of fault messages is sent by the right rear bumper radar sensor via engine compartment CAN to the instrument cluster and via engine compartment CAN, central gateway control unit and interior CAN to the left front door control unit or right front door control unit, which then actuates the corresponding Blind Spot Assist readiness and warning indicator.
Blind Spot Assist ready, shown on left outside mirror
If, at a speed of v ≥ 30 km/h, a vehicle is located in the sensing range of the rear bumper radar sensors, the driver is notified of it by the Blind Spot Assist readiness and warning indicator turning red in the outside mirror on the side of the vehicle on which the vehicle is in the blind spot. Overtaking vehicles are reliably detected up to a relative speed of v = 35 km/h. Vehicles with a higher relative speed may-under certain circumstances - be detected too late or not at all. If the driver tries to initiate a lane change despite the lighting up of the readiness and warning indicator for the Blind Spot Assist and signals this by operating the combination switch (set flasher), in addition the output of a one-time dual warning tone takes place by the warning buzzer in the IC. The request for output of warning tone is sent by the rear bumper radar sensor to the instrument cluster via engine compartment CAN, which then actuates the warning buzzer directly. The readiness and warning indicator for Blind Spot Assist flashes red. If the vehicle leaves the rear bumper radar sensor system's sensing range, the red flashing Blind Spot Assist readiness and warning indicator is switched off.
The signal curve for issue of warning messages corresponds to that of the display for system readiness.
The steering column tube module reads in the switch position of the combination switch directly and sends this via engine compartment CAN to the rear bumper radar sensors.
Blind Spot Assist warning indicator, shown on left outside mirror
The preconditions for the indication of the system readiness and for the output of the visual warning messages can be found in the following table.
| Operating state | Blind Spot Assist readiness and warning indicator off | Blind Spot Assist readiness and warning indicator, yellow on | Blind Spot Assist readiness and warning indicator, red on | Blind Spot Assist readiness and warning indicator, flashing red |
|---|---|---|---|---|
| Circuit 15 OFF | X | |||
| Terminal 15 ON (t < 1.5 s) | X | |||
| Terminal 15 ON (t > 1.5 s) | X | |||
| Engine running | X | |||
| Vehicle accelerates, Vehicle speed v ≥ 30 km/h | X | |||
| Vehicle decelerates, Vehicle speed v ≤ 25 km/h | X | |||
| Trailer recognized (with code (550) Trailer hitch or code (553) Mechanically folding trailer hitch) | X | |||
| Drive position "R" engaged | X | |||
| Vehicle recognized in blind spot | X | |||
| Flasher set, vehicle recognized in blind spot | X | |||
| Radar sensor system automatically switched off (model 251 up to 31.5.13, model 164) | X | |||
| Fault in Blind Spot Assist system | X |
| Electrical function schematic, blind spot assistant | MODEL 164.1/8 as of model year 2011 with CODE 234 (Blind Spot Monitoring) | PE54.71-P-2051-97MAA | |
| MODEL 251.0/1 as of model year 2011 with CODE 234 (Blind Spot Monitoring) | PE54.71-P-2051-97RAA | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998GV |