What does it mean?
B1783 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Occupant Classification Sensor Rear RH Circuit Malfunction .
Symptoms
- Airbag warning lamp lit with the occupant detection system switched off
- Passenger airbag indicator not matching the actual occupant
- Passenger airbag possibly disabled with an adult seated, or armed with the seat empty
- Scan tool shows one corner value stuck, at zero or far from the other three
- Calibration attempt fails or aborts
Likely causes
- Rear right sensor connector corroded, unplugged or only partly latched after seat work
- Lead chafed or pinched between the seat frame, the rail and the centre console
- Wet carpet or a spilled drink corroding the terminals at the seat base
- Load cell damaged by a heavy object placed on that corner of the cushion, or by a hard impact
- Mounting bolts loose or the seat frame twisted so the rear right corner carries a false preload
- Objects stored under the seat pressing on the frame and biasing the reading
- Occupant classification module fault
How to fix it
- Read codes and record all four corner values with an empty seat
- Clear out anything under or on the seat, including thick covers and cushions
- Check the rear right connector for corrosion, moisture and pin condition, and confirm it is fully latched
- Slide the seat through its range while wiggling the lead and watching the live value
- Verify mounting bolt condition and torque and check the frame is not touching the console or floor bracket
- Run the manufacturer's zero or calibration routine, mandatory whenever the seat has been disturbed
- Replace the sensor or seat frame assembly as specified, recalibrate and verify with a known weight