Seat-belt warning
| Seat-belt warning |
The passenger seat contains a sensor which detects if the seat is occupied/loaded. Each seatbelt buckle has a switch which is connected to the airbag control module. If the seatbelt is not fastened, the control module sends a reminder that is indicated as follows:
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seatbelt reminder lamp ”FASTEN BELTS”
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audible signal (SID)
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text message on the SID (certain markets only).
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The seatbelt reminder lamp lights each time the ignition is turned ON and remains on until the belts are fastened.
| Description of operation |
The seatbelt reminder lamp lights when the ignition is in the ON position (+15 and +54) and when the driver or passenger has not buckled up.
The seatbelt switch (70D/70P) is closed when the seatbelt is not buckled up and open when the tongue is inserted.
The front passenger seat cushion has a load sensor. The passenger seat sensor (614P) is connected across pins 5 and 21 of the TWICE. The sensor is supplied with power via pin 5 and a resistor in TWICE, and grounded via pin 21.
The resistance of the sensor varies with the load. TWICE measures the voltage across the sensor. When the resistance of the sensor is lower than 50 kohm, the seat is presumed to be occupied.
Burn-off
To ensure the best possible contact between the sensor connectors, the TWICE sends a voltage across pins 5 and 21 to burn off any oxide. This voltage is supplied for 1 second when the ignition is turned ON.To ensure that the burn-off current is sufficiently high, there is a diode connected in parallel across the sensor connections. The resistance of the diode is low, which means that the burn-off current runs through the diode instead of the sensor.
| Indication |
The seatbelt reminder lamp (72) is supplied with +15 from fuse 26.
The reminder lamp is grounded via pin 28 of the TWICE.
If the seatbelt is not fastened, a further reminder is given. This is shown as a message on the SID.
An audible signal is also given as a reminder to buckle up. The signal sounds for a short while if a front seat passenger has not buckled up. When the seatbelts have fastened, the signal is silenced.
The airbag control module sends a bus message and the SID emits an audible signal.
| Diagnostics |
If there is a fault in the seatbelt reminder lamp circuit, DTC B1210 is generated in TWICE. The DTC is generated in the event of:
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An open circuit or short circuit to ground
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A short-circuit to B+.
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The DTC is not generated if the voltage is lower than 11V or during diagnostic communication. The control module output can be activated with the diagnostic tool
| Bus communication |
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Used information
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Sensor system
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Ignition +54 (On/Off)
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DICE
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DICE provides the system with information on +54.
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Sent information
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User System
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Passenger seat occupied (yes/no)
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ACC
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Acoustic reminder (On/Off)
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SID
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