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Occupant Classification System (Diagnostic Codes): Overview Lexus LX J200

Airbag 5 illustrations ~606 words

DESCRIPTION

The passenger side buckle switch circuit consists of the occupant classification ECU and the front seat inner belt RH.

DTC B1771 is stored when a malfunction is detected in the passenger side buckle switch circuit.

DTC CodeDTC Detection ConditionTrouble Area
B1771When one of the following conditions is met: The occupant classification ECU receives a line short circuit signal, open circuit signal, short circuit to ground signal or short circuit to B+ signal in the passenger side buckle switch circuit for 2 seconds. A passenger side buckle switch malfunction. An occupant classification ECU malfunction.Front seat wire RH Front seat inner belt assembly RH (passenger side buckle switch) No. 1 seat cushion assembly (occupant classification ECU)

HINT

When DTC B1650 is stored as a result of troubleshooting for the "Airbag System", check the DTCs stored in the occupant classification ECU. When DTC B1771 is output, perform troubleshooting for it first.

Scheme 377

Scheme 377: WIRING DIAGRAM

The seat position sensor circuit consists of the occupant classification ECU and the seat position sensor.

The seat position sensor sends the seat position signal to the occupant classification ECU to control the dual stage deployment of the front passenger airbag.

DTC B1772 is stored when a malfunction is detected in the seat position sensor circuit.

DTC CodeDTC Detection ConditionTrouble Area
B1772When one of the following conditions is met: The occupant classification ECU receives a line short circuit signal, open circuit signal, short circuit to ground signal or short circuit to B+ signal in the seat position sensor circuit for 2 seconds. A seat position sensor malfunction. An occupant classification ECU malfunction.Front seat wire RH Seat position sensor No. 1 seat cushion assembly (occupant classification ECU)

HINT

  1. When DTC B1650 is output as a result of troubleshooting for the "Airbag System", check the DTCs stored in the occupant classification ECU, and perform troubleshooting for those DTCs first.
  2. Use the Techstream to check for DTCs of the occupant classification ECU, otherwise the DTC cannot be read.

Scheme 378

Scheme 378: WIRING DIAGRAM

The seat belt tension sensor circuit consists of the occupant classification ECU and the seat belt tension sensor.

The seat belt tension sensor sends the seat belt tension signal to the occupant classification ECU.

DTC B1773 and B1776 are stored when a malfunction is detected in the seat belt tension sensor circuit.

DTC CodeDTC Detection ConditionTrouble Area
B1773 B1776When one of the following conditions is met: The occupant classification ECU receives a line short circuit signal, open circuit signal, short circuit to ground signal or short circuit to B+ signal in the seat belt tension sensor circuit for 2 seconds. A seat belt tension sensor malfunction. An occupant classification ECU malfunction.Front seat wire RH Front seat outer belt assembly RH (seat belt tension sensor) No. 1 seat cushion assembly (occupant classification ECU)

HINT

When DTC B1650 is stored as a result of troubleshooting for the "Airbag System", check the DTCs stored in the occupant classification ECU. When DTC B1773 and B1776 are output, perform troubleshooting for those DTCs first.

Scheme 379

Scheme 379: WIRING DIAGRAM

The pressure sensor circuit consists of the occupant classification ECU and the occupant detection sensor.

The occupant detection sensor sends the pressure signal to the occupant classification ECU.

DTC B1774 and B1775 are stored when a malfunction is detected in the pressure sensor circuit.

DTC CodeDTC Detection ConditionTrouble Area
B1774 B1775When one of the following conditions is met: The occupant classification ECU receives a line short circuit signal, open circuit signal, short circuit to ground signal or short circuit to B+ signal in the occupant detection sensor circuit for 2 seconds. An occupant detection sensor malfunction. An occupant classification ECU malfunction.Front seat wire RH No. 1 seat cushion assembly (occupant classification ECU and occupant detection sensor)

HINT

When DTC B1650 is stored as a result of troubleshooting for the "Airbag System", check the DTCs stored in the occupant classification ECU. When DTC B1774 and B1775 are output, perform troubleshooting for those DTCs first.

Scheme 380

Scheme 380: WIRING DIAGRAM

The center airbag sensor communication circuit consists of the occupant classification ECU and the center airbag sensor.

DTC B1790 is stored when a malfunction is detected in the center airbag sensor communication circuit.

DTC CodeDTC Detection ConditionTrouble Area
B1790When one of the following conditions is met: The occupant classification ECU receives a line short circuit signal, open circuit signal, short circuit to ground signal or short circuit to B+ signal in the center airbag sensor circuit for 2 seconds. A center airbag sensor malfunction. An occupant classification ECU malfunction.No. 2 floor wire Front seat wire RH No. 1 seat cushion assembly (occupant classification ECU) Center airbag sensor assembly

HINT

When DTC B1650 is stored as a result of troubleshooting for the "Airbag System", check the DTCs stored in the occupant classification ECU. When DTC B1790 is output, perform troubleshooting for it first.

Scheme 381

Scheme 381: WIRING DIAGRAM

DTC B1795 is stored when a malfunction is detected in the occupant classification ECU.

DTC CodeDTC Detection ConditionTrouble Area
B1795An occupant classification ECU malfunction.No. 1 seat cushion assembly (occupant classification ECU)

HINT

When DTC B1650 is stored as a result of troubleshooting for the "Airbag System", check the DTCs stored in the occupant classification ECU. When DTC B1795 is output, perform troubleshooting for it first.

DTC B1797 is output when one of the following conditions is met

  1. Zero point calibration is performed when the conditions for the calibration are not satisfied.
  1. Zero point calibration has failed.
ItemCondition
DTCNot recorded
Front passenger seat occupantVacant
Front passenger side buckle switchOFF (The seat belt is not fastened)
ECU temperature0 to 46°C (32 to 115°F)
Filtered pressure38 to 75 count

CONDITION FOR THE ZERO POINT CALIBRATION

DTC CodeDTC Detection ConditionTrouble Area
B1797One of the following conditions is met: Zero point calibration is performed when the conditions for calibration are not satisfied. Zero point calibration has failed.There is no malfunction if this DTC is not output again after performing occupant classification system zero point calibration No. 1 seat cushion assembly (occupant detection sensor)

HINT

When DTC B1650 is stored as a result of troubleshooting for the "Airbag System", check the DTCs stored in the occupant classification ECU. When DTC B1797 is output, perform troubleshooting for it first.

The occupant classification system detects the front passenger seat condition. It then informs a passenger of the front passenger airbag and front seat airbag condition (activated/not activated) by the passenger airbag ON/OFF indicator.

HINT

Approximately 6 seconds after the engine switch is turned on (IG), the passenger airbag ON/OFF indicator will be ON/OFF depending on the conditions listed below.

Front Passenger Seat ConditionPassenger Airbag ON/OFF IndicatorSRS Warning Light
ON IndicatorOFF Indicator
Adult is seatedOnOffOff
Child is seatedOffOnOff
VacantOffOffOff
Occupant classification system failureOffOnOn