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 fitted. There are 4 different sensors:
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Driver, 5-door
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Passenger, 5-door
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Driver, 3-door
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Passenger, 3-door
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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 supplies the side impact sensor with current when the ignition switch is turned to the ON position, whereupon the sensor immediately responds with its status. The status message is subsequently sent at regular intervals under normal operating conditions. If the SRS control module has been configured for side airbags but cannot make contact with either of the side impact sensors within 10-20 seconds, a side impact sensor diagnostic trouble code will be generated. The control module continues its attempts to establish communication with the side impact sensor that gave rise to the trouble code.
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 side airbag activation command from the side impact sensor to the control module must consist of several messages. This is to avoid the danger of the control module activating the side airbag because of some 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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