Side impact sensor
| Side impact sensor |
Two leads from the SRS control module are connected to the side impact sensor. They supply current to the sensor and are also used for communication between the side impact sensor and the control module.
The side impact sensor is specific to the door and car in which it is mounted. There are 4 different sensors:
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Driver, 5D
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Passenger, 5D
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Driver, 3D
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Passenger, 3D
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The side impact sensor on the driver's side is connected to pins 41 and 42 of the control module. The sensor on the passenger's side is connected to pins 43 and 44 of the control module.
Incorporated in the side impact sensor is a pressure sensor which reacts to comparatively small air pressure changes inside the door. A microprocessor in the side impact sensor processes the pressure information and determines whether it corresponds to the limits that have been defined as constituting a collision.
The side impact sensor communicates by modulating the supply of current from the SRS control module. The changes are then registered by the microprocessor in the control module.
The communication may consist of the following messages:
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Identification of driver side or passenger side.
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Status of side impact sensor, whether defective or OK.
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Activation of side airbag.
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The SRS control module starts to supply the side impact sensor with current when the ignition is turned ON and the sensor responds spontaneously with its status. Status messages are subsequently sent at regular intervals during normal operation. If the SRS control module is configured for side airbags and cannot establish contact with any of the side impact sensors within 10-20 seconds, a side impact sensor diagnostic trouble code will be generated. The control module continues attempting to restore communication with the side impact sensor that caused the fault.
On the basis of information from the side impact sensor, the SRS control module reaches a decision concerning side impact sensor related diagnostic trouble codes.
A command from the side impact sensor telling the control module to activate a side airbag must consist of several messages. This avoids the danger of the control module activating the side airbag due to electronic interference.
A diagnostic trouble code is generated when a side airbag has been activated and further communication with the side impact sensor will be ignored by the control module.
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