PRE-RELEASE
Distance sensors
| Distance sensors |
The four distance sensors are located in the rear bumper. They are mounted in identical plastic brackets that can be interchanged.
The sensors are named as follows:
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Left-hand outer distance sensor (RL)
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Left-hand centre distance sensor (RLC)
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Right-hand centre distance sensor (RRC)
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Right-hand outer distance sensor (RR)
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Each distance sensor contains a diaphragm that works both as a speaker unit and microphone unit.
The distance sensors emit a wide-angle ultrasound signal (120° laterally and 60° vertically) and detect the reflected sound signals. The signals are converted to a digital signal that is sent to the control module for calculation of the closest object.
The distance sensors are active when the control module is in mode 2 or 3, i.e. Active and Detected
The distance sensors work according to a loop (controlled by the control module), which is repeated 3 times per second. The loop is as follows:
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Step 1:
Sensor 1 - RL - emits an ultrasound signal and listens with sensors 1 and 2.
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Step 2:
Sensor 2 - RLC - emits an ultrasound signal and listens with sensors 1 and 2.
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Step 3:
Sensor 2 - RLC - emits an ultrasound signal and listens with sensors 2 and 3.
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Step 4:
Sensor 3 - RRC - emits an ultrasound signal and listens with sensors 2 and 3.
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Step 5:
Sensor 3 - RRC - emits an ultrasound signal and listens with sensors 3 and 4.
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Step 6:
Sensor 4 - RR - emits an ultrasound signal and listens with sensors 3 and 4.
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After a completed loop, the control module checks the sensors and calculates using Pythagoras' theorem (a 2 +b 2 =c 2 ) which object is closest to the rear or side of the car, i.e. the object that the driver will be informed of.
| Diagnostics |
The control module monitors its own functionality and inputs and outputs.
The distance sensors are checked 10 times/second in modes 2 and 3.
In the event of a fault in a distance sensor or its communication with the control module, the following diagnostic trouble codes are generated:
| Diagnostic trouble code | Sensor | |
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B2906
B2916 B2926 B2936 |
RR
RRC RLC RL |
Communication cable shorted to B+
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B2907
B2917 B2927 B2937 |
RR
RRC RLC RL |
Communication cable broken or shorted to ground, or break in supply
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B2908
B2918 B2928 B2938 |
RR
RRC RLC RL |
Open ground circuit, short to ground or B+, or internal sensor error
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B2909
B2919 B2929 B2939 |
RR
RRC RLC RL |
Internal fault
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B2950
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Sensor power supply shorted to ground
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RR:
Right-hand outer sensor
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RRC:
Right-hand centre sensor
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RLC:
Left-hand centre sensor
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RL:
Left-hand outer sensor
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For further information about fault diagnosis, see
Fault diagnosis strategy for electronic systems .
