Occupant Classification System (Diagnostics - Introduction): Other Lexus LX J200

PRECAUTION

Note. Replace the occupant classification ECU, occupant detection sensor, seat cushion cover pad, seat cushion cover and seat cushion seat heater as a 5 part set (see supply set part No.). When the cable is disconnected from the negative (-) battery terminal, the memory settings of each system will be cleared. Because of this, be sure to write down the settings of each system before starting work. When work is finished, reset the settings of each system as before. Never use a backup power supply from outside the vehicle to avoid erasing the memory in a system. w/ Navigation system: After the engine switch is turned off, the HDD navigation system requires approximately 6 minutes to record various types of memory and settings. As a result, after turning the engine switch off, wait 6 minutes or more before disconnecting the cable from the negative (-) battery terminal.

1. INSPECTION PROCEDURE FOR VEHICLE INVOLVED IN ACCIDENT Perform zero point calibration and sensitivity check if any of the following conditions apply. Refer to «INITIALIZATION»(ref-385313-S14540855742011021400000) . The No. 1 seat cushion (occupant classification ECU) is replaced. The passenger airbag ON/OFF indicator indicates ("OFF") when the front passenger seat is not occupied. The vehicle is brought to the workshop for repair due to an accident or a collision.
2. PRECAUTIONS WHEN USING THE TECHSTREAM When using the Techstream with the engine switch off to troubleshoot: Connect the Techstream to the vehicle, and turn a courtesy light switch on and off at 1.5 second intervals until communication between the Techstream and vehicle begins. After all DTCs are cleared, check if the trouble occurs again 6 seconds after the engine switch is turned on (IG).

Scheme 373

Scheme 374

Scheme 375

1. GENERAL DESCRIPTION In the occupant classification system, the occupant classification ECU calculates the weight of the front passenger based on a signal from the occupant detection sensor. This system judges the occupant to be a child when it detects a weight of less than 27.3 kg (60.7 lb), and disables the front passenger airbag and front seat airbag RH. This system is mainly composed of the occupant detection sensor that detects the load on the front passenger seat. The occupant classification ECU controls the system, and the passenger airbag ON/OFF indicator indicates the ON/OFF condition of the front passenger airbag and front seat airbag RH.
2. OCCUPANT DETECTION SENSOR The occupant detection sensor consists of a gel mat and a pressure sensor. When weight is applied to the gel mat, the pressure applied through the silicone to the pressure sensor changes. The pressure sensor converts these changes into voltages and transmits them to the occupant classification ECU. The occupant detection sensor is installed between the seat cushion frame and seat cushion pad. The pressure sensor is installed on the seat frame. The pressure sensor detects the pressure applied to the front passenger seat. The occupant classification ECU determines whether the front passenger airbag and front seat airbag RH are deployed based on signals from the pressure sensor.
3. SEAT BELT TENSION SENSOR The seat belt tension sensor is installed on the front seat outer belt to control the CRS (Child Restraint System).

REGISTRATION

1. REGISTRATION NOTE: If any DTCs related to the occupant classification ECU are output, troubleshoot those DTCs by referring to the Diagnostic Trouble Code Chart. When ECU data saving or loading operations cannot be performed, replace the No. 1 seat cushion (occupant classification ECU and occupant detection sensor). HINT: When the No. 1 seat cushion (occupant classification ECU) is replaced, the previous ECU data must be saved in the Techstream and loaded into the new ECU by following the flowchart below. Until the data from the previous ECU are loaded into the new occupant classification ECU, these data are not cleared even when the Techstream is turned off. Connect the Techstream to the DLC3. Turn the engine switch on (IG). Store the occupant classification ECU data in the Techstream by following the prompts on the Techstream screen. HINT: If the ECU data cannot be stored in the Techstream, replace the No. 1 seat cushion (occupant classification ECU and occupant detection sensor). Turn the engine switch on (IG). Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds. Replace the No. 1 seat cushion (occupant classification ECU). Refer to «DISASSEMBLY»(ref-385219-S07493195202011021400000) . Connect the cable to the negative (-) battery terminal. Turn the engine switch on (IG). Load the data from the previous ECU stored in the Techstream into the newly installed ECU by following the prompts on the Techstream screen. Turn the engine switch off. Turn the engine switch on (IG). Clear the DTCs stored in the memory. Refer to «DTC CHECK / CLEAR»(ref-385313-S18166417782011021400000) . HINT: If DTCs are not cleared at this time, past DTCs will remain.

INITIALIZATION

Note. Make sure that the front passenger seat is not occupied before performing the operation.

HINT

Perform zero point calibration if any of the following conditions is met

1. The No. 1 seat cushion (occupant classification ECU) is replaced.
2. The passenger airbag ON/OFF indicator indicates ("OFF") when the front passenger seat is not occupied.
3. The vehicle is brought to the workshop for repair due to an accident or a collision.

Scheme 376

1. ZERO POINT CALIBRATION Zero point calibration procedures Check that all of the following conditions are met: The vehicle is parked on a level surface. No objects are placed on the front passenger seat. The front passenger seat belt buckle switch is off. Adjust the seat position according to the table below. Adjustment Item Position Slide Direction Rear most position Reclining Angle Upright position Front vertical Height Upper most position Lifter Height Lower most position Connect the Techstream to the DLC3. Turn the engine switch on (IG). Perform zero point calibration by following the prompts on the Techstream screen. HINT: Refer to the Techstream operator's manual for further details. If the zero point calibration is performed when the calibration conditions are not satisfied, DTC B1797 is output. If the zero point calibration has failed, DTC B1797 is output. If After Exchange is selected before the previous ECU data are stored in the Techstream, the display screen returns to System Select: Body Electrical / Occupant Detection. OK "Zero Point Calibration is complete" is displayed. Item Procedure DTC Check for DTCs and perform troubleshooting Write error Replace No. 1 seat cushion (occupant classification ECU and occupant detection sensor) Temperature Check value of Thermistor temperature output in Data List Pressure Check value of Filtered pressure sensor output in Data List Crash counter
2. SENSITIVITY CHECK Sensitivity check procedures Turn the engine switch off. Place a weight of 20 kg (44.0 lb) on the front passenger seat. NOTE: Do not allow the weight to come into contact with the seatback when placing it on the seat cushion. Place the weight in the area shown in the illustration. Turn the engine switch on (IG), and wait for at least 6 seconds. Check that the passenger airbag ON/OFF indicator indicates ("OFF"). OK Passenger airbag ON/OFF indicator indicates ("OFF"). Add a weight of 30 kg (66.1 lb) to the front passenger seat (total 50 kg (110.2 lb)). NOTE: Do not allow the weight to come into contact with the seatback when placing it on the seat cushion. Check that the passenger airbag ON/OFF indicator indicates ("ON"). OK Passenger airbag ON/OFF indicator indicates ("ON").

FAIL-SAFE CHART

1. FAIL SAFE FUNCTION The following chart shows the status of the controls when the system is normal and malfunctioning. The passenger airbag ON/OFF indicator ("ON" and "OFF") comes on for approximately 4 seconds, then goes off for approximately 2 seconds. Approximately 6 seconds after the engine switch is turned on (IG), the passenger airbag ON/OFF indicator will show ("ON" or "OFF") depending on the conditions listed below. Condition ON Indicator OFF Indicator Front Passenger Airbag and Front Passenger Side Knee Airbag Front Seat Airbag RH Front Seat Belt Pretensioner RH Curtain Shield Airbag Adult is seated On Off o o o o Child is seated Off On X X o o Vacant Off On X X X o Failure 1 (SRS warning light OFF) Off On X X o o Failure 2 (SRS warning light ON) Off On X X X X HINT: o: Deployable X: Not deployable