9-3 SE Hatchback (9400) L4-2.0L Turbo (B205) HO (2000)
/l4-2.0l_turbo_(b205)_ho/Page-2460001.png)
Seat Belt Reminder Lamp: Description and Operation
Seat Belt Warning
The seat belt warning checks that the driver and front-seat passenger have fastened their seat belts.
The passenger seat has a sensor that detects when the seat is occupied/loaded. Each buckle has a contact connected with TWICE. If the belt is not
fastened, TWICE sends a warning, which is indicated in the following way:
-
belt warning light "FASTEN BELTS"
-
acoustic signal (SID).
The belt warning light is turned on each time the ignition is turned ON and stays alight until the seat belt is fastened.
Description of operation
The belt warning light is turned on when the ignition is ON (+15 and +54 circuits) and when the driver's or front-seat passenger's seat belt is not fastened.
The belt contact (70D/70P) is closed when the seat belt is not fastened, and open when it is.
The front passenger seat cushion contains a sensor which detects load. The passenger seat sensor (614P) is connected across pins 5 and 21 of TWICE.
Voltage is supplied to the sensor from pin 5 via a resistor in TWICE, and pin 21 is grounded.
The resistance of the sensor varies depending on the load exerted on it. TWICE detects the voltage across the sensor. When the resistance is below 50 k
ohm, the load on the seat is considered to mean that it is occupied.
Burn-off
To maintain the best possible contact in the sensor connections, TWICE sends a voltage across pins 5 and 21 to burn off any oxide. This is done for 1
second with the ignition ON.
To ensure that the burn-off current remains sufficiently high, a diode is connected in parallel across the sensor connectors. The diode conducts at low
resistance, which means that the burn off current passes through the diode instead of the sensor.
