Occupant Classification System (diagnostics - Introduction) Lexus IS F I

PRECAUTION

1. INSPECTION PROCEDURE FOR VEHICLE INVOLVED IN ACCIDENT Perform zero point calibration and sensitivity check if any of the following conditions are met: The 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.

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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 classification sensor. This system judges the occupant to be a child when it detects a weight of less than 27.3 kg (60 lb), and disables the front passenger airbag, front passenger side knee airbag and front seat side airbag RH. This system is mainly composed of the occupant classification 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, front passenger side knee airbag and front seat side airbag RH.
2. OCCUPANT CLASSIFICATION SENSOR The occupant classification sensor consists of the gel mat and the 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 classification 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 as a seated passenger. The occupant classification ECU determines whether the front passenger airbag, front passenger side knee airbag and front seat side 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 detect a CRS (Child Restraint System).

HOW TO PROCEED WITH TROUBLESHOOTING

HINT

*: Use the Techstream.

1. VEHICLE BROUGHT TO WORKSHOP NEXT: Go to next step
2. CUSTOMER PROBLEM ANALYSIS Confirm problem symptoms. Refer to «HOW TO PROCEED WITH TROUBLESHOOTING»(/lexus/is-f/i-2007-2014/remont/hoistjack/#introduction) . NEXT: Go to next step
3. PASSENGER AIRBAG ON/OFF INDICATOR CHECK Proceed to Diagnosis System. Refer to «DIAGNOSTIC TROUBLE CODE CHART»(/lexus/is-f/i-2007-2014/remont/airbag/#occupant-classification-system-diagnostics-introduction__diagnostic-trouble-code-chart) . NEXT: Go to next step
4. DTC CHECK (Present and Past DTCs)* Proceed to DTC Check / Clear. Refer to «DTC CHECK / CLEAR»(/lexus/is-f/i-2007-2014/remont/airbag/#occupant-classification-system-diagnostics-introduction__dtc-check-clear) . Result Result Proceed to DTC is output. A DTC is not output. B B --> GO TO PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(/lexus/is-f/i-2007-2014/remont/airbag/#occupant-classification-system-diagnostics-introduction__problem-symptoms-table) A: Go to next step
5. DIAGNOSTIC TROUBLE CODE CHART Proceed to Diagnostic Trouble Code Chart. Refer to «DIAGNOSTIC TROUBLE CODE CHART»(/lexus/is-f/i-2007-2014/remont/airbag/#occupant-classification-system-diagnostics-introduction__diagnostic-trouble-code-chart) . NEXT: Go to next step
6. CIRCUIT INSPECTION* NEXT: Go to next step
7. REPAIR NEXT: Go to next step
8. CLEAR DTCS (Present and Past DTCs)* Proceed to DTC Check / Clear. Refer to «DTC CHECK / CLEAR»(/lexus/is-f/i-2007-2014/remont/airbag/#occupant-classification-system-diagnostics-introduction__dtc-check-clear) . NEXT: Go to next step
9. DTCS CHECK (Present and Past DTCs)* Proceed to DTC Check / Clear. Refer to «DTC CHECK / CLEAR»(/lexus/is-f/i-2007-2014/remont/airbag/#occupant-classification-system-diagnostics-introduction__dtc-check-clear) . Result Result Proceed to DTC is not output. A DTC is output. B B --> GO TO DIAGNOSTIC TROUBLE CODE CHART. Refer to «DIAGNOSTIC TROUBLE CODE CHART»(/lexus/is-f/i-2007-2014/remont/airbag/#occupant-classification-system-diagnostics-introduction__diagnostic-trouble-code-chart) A: Go to next step
10. SYMPTOM SIMULATION Check the passenger airbag ON/OFF indicator condition. Result Result Proceed to Passenger airbag ON/OFF indicator operates normally. A Passenger airbag ON/OFF indicator ("OFF") and SRS warning light come on. B B --> GO TO DIAGNOSTIC TROUBLE CODE CHART. Refer to «DIAGNOSTIC TROUBLE CODE CHART»(/lexus/is-f/i-2007-2014/remont/airbag/#occupant-classification-system-diagnostics-introduction__diagnostic-trouble-code-chart) A: Go to next step
11. CONFIRMATION TEST NEXT --> END

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 front seat cushion assembly (with occupant classification ECU and occupant classification sensor). HINT: When the 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 erased even when the Techstream is turned off. ECU EXCHANGE PROCEDURE (Before Exchange) describes the procedure to save the data in the Techstream from the occupant classification ECU currently installed on the vehicle. ECU EXCHANGE PROCEDURE (After Exchange) describes the procedure to load the data from the previous ECU, or stored in the Techstream, into the new ECU. 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 front seat cushion assembly (with occupant classification ECU and occupant classification sensor). Turn the engine switch off. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds. Replace the occupant classification ECU. Refer to «REMOVAL»(/lexus/is-f/i-2007-2014/remont/restraints-control-systems/#supplemental-restraint-system-service-information) . 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»(/lexus/is-f/i-2007-2014/remont/airbag/#occupant-classification-system-diagnostics-introduction__dtc-check-clear) . 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 the zero point calibration if any of the following conditions is met

1. The 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.

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1. ZERO POINT CALIBRATION Zero point calibration procedures Check that all of the following conditions are met: The vehicle is parked on a flat 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 Rearmost position Reclining Angle Upright position Headrest Height Lowest position Lifter Height Lowest position Connect the Techstream to the DLC3. Turn the engine switch on (IG). Enter the following menus: Body Electrical / Occupant Detection / Utility / Zero Point Calibration. Perform the 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 CONDITION SELECT ECU: Occupant Detect. Item Procedure DTC Perform DTC check and repair Write error Replace front seat cushion assembly (with occupant classification ECU and occupant classification sensor) Temperature Check value of Thermistor Temperature Output in ECU Data List Pressure Check value of Filtered Pressure Sensor Output in ECU Data List Crash counter
2. SENSITIVITY CHECK Sensitivity check procedures Turn the engine switch off. Place a 20 kg (44.0 lb) weight 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 The passenger airbag ON/OFF indicator indicates OFF. Add a 30 kg (66.1 lb) weight 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. Place the weight in the area shown in the illustration. Check that the passenger airbag ON/OFF indicator indicates ON. OK The passenger airbag ON/OFF indicator indicates ON.

PROBLEM SYMPTOMS TABLE

HINT

1. Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of probability in the "Suspected Area" column of the table. Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.
2. Inspect the fuses and relays related to this system before inspecting the suspected areas below.

OCCUPANT CLASSIFICATION SYSTEM

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1. OCCUPANT CLASSIFICATION ECU Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition T16-5 (GND) - Body ground W-B - Body ground Occupant classification ECU ground line Always Below 1 V T16-6 (PS) - T16-15 (GPS) LG - W Pressure sensor signal line Engine switch on (IG) 0 to 5 V T16-7 (VPS) - T16-5 (GND) Y - W-B Pressure sensor +B line Engine switch on (IG) 4.75 to 5.25 V T16-8 (GBT) - T16-5 (GND) G - W-B Belt tension sensor ground line Always Below 1 V T16-9 (IG) - T16-5 (GND) B - W-B Occupant classification ECU +B line Engine switch on (IG) 10 to 14 V T16-10 (DIA) - T16-5 (GND) W - W-B Diagnosis (DLC3) Engine switch on (IG) Pulse generation T16-11 (FSR+) - T16-12 (FSR-) W - B Center airbag sensor assembly communication line Engine switch on (IG) Pulse generation T16-12 (FSR-) - T16-5 (GND) B - W-B Center airbag sensor assembly communication line (-) Always Below 1 V T16-13 (BSW) - T16-14 (BGND) B - GR Passenger side buckle switch line Engine switch on (IG) Low: 4 to 7 mA Hi: 12 to 18 mA T16-14 (BGND) - T16-5 (GND) GR - W-B Passenger side buckle switch ground line Always Below 1 V T16-15 (GPS) - T16-5 (GND) W - W-B Pressure sensor ground line Always Below 1 V T16-16 (BT) - T16-5 (GND) R - W-B Belt tension sensor signal line Engine switch on (IG) 0 to 5 V T16-17 (VBT) - T16-5 (GND) P - W-B Belt tension sensor +B line Engine switch on (IG) 4.75 to 5.25 V

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1. CHECK DLC3 Check the DLC3. Refer to «GENERAL INFORMATION»(/lexus/is-f/i-2007-2014/remont/hoistjack/#introduction) .
2. SYMPTOM SIMULATION HINT: The most difficult case in troubleshooting is when no symptoms occur. In such cases, a thorough customer problem analysis must be carried out. Then the same or similar conditions and the environment in which the problem occurred in the customer's vehicle should be simulated. No matter how experienced or skilled a technician may be, if he proceeds to troubleshooting without confirming the problem symptoms, he will likely overlook something important and make a wrong guess at some points in the repair operation. This leads to a standstill in troubleshooting. Vibration method: When vibration seems to be the major cause. HINT: Perform the simulation method only during the primary check period of approximately 6 seconds after the engine switch is turned on (IG). Slightly vibrate the part of the sensor considered to be the problem cause with your fingers and check whether the malfunction occurs. HINT: Shaking the relays too strongly may result in open relays. Slightly shake the connector vertically and horizontally. Slightly shake the wire harness vertically and horizontally. The connector joint and fulcrum of the vibration are the major areas to be checked thoroughly.
3. FUNCTION OF PASSENGER AIRBAG ON/OFF INDICATOR Initial check. Turn the engine switch on (IG). 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. Front Passenger Seat Condition Passenger Airbag ON/OFF Indicator SRS Warning Light ON Indicator OFF Indicator Vacant OFF OFF OFF Adult is seated ON OFF OFF Child is seated. OFF ON OFF Child restraint system is set. OFF ON OFF Front passenger occupant classification failure OFF ON ON HINT: The passenger airbag ON/OFF indicator is based on the timing chart below in order to check the indicator light circuit. When the occupant classification system has trouble, both the SRS warning light and the passenger airbag ON/OFF indicator ("OFF") come on. In this case, check the DTCs in the airbag system first.
4. CHECK PASSENGER AIRBAG ON/OFF INDICATOR Turn the engine switch on (IG). Check that the passenger airbag ON/OFF indicator ("ON" and "OFF") comes on for approximately 4 seconds, then goes off for approximately 2 seconds. HINT: Refer to the table in the previous step regarding the passenger airbag ON/OFF indicator when the engine switch is turned on (IG) and approximately 6 seconds pass. (Refer to step 3 )

DTC CHECK / CLEAR

HINT

Use the Techstream to read and clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be read and cleared.

1. DTC CHECK Turn the engine switch off. Connect the Techstream to the DLC3. Turn the engine switch on (IG) and turn the Techstream on. Enter the following menus: Body Electrical / Occupant Detection / Trouble Code. Check the DTCs by following the prompts on the Techstream screen. HINT: Refer to the Techstream operator's manual for further details.
2. DTC CLEAR Turn the engine switch off. Connect the Techstream to the DLC3. Turn the engine switch on (IG) and turn the Techstream on. Enter the following menus: Body Electrical / Occupant Detection / Trouble Code. Clear the DTCs by following the prompts on the Techstream screen. HINT: Refer to the Techstream operator's manual for further details.

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 Front Passenger Side Knee Airbag RH Front Seat Side Airbag RH Front Seat Belt Pretensioner RH Curtain Shield Airbag RH Adult is seated ON OFF o o o o o Child is seated OFF ON - - - o o Vacant OFF OFF - - - - o Failure OFF ON - - - o o HINT: o: Deployable -: Not deployable

DATA LIST / ACTIVE TEST

HINT

Using the Techstream to read the Data List allows the values or states of switches, sensors, actuators and other items to be read without removing any parts. This non-intrusive inspection can be very useful because intermittent conditions or signals may be discovered before parts or wiring is disturbed. Reading the Data List information early in troubleshooting is one way to save diagnostic time.

Note. In the table below, the values listed under "Normal Condition" are reference values. Do not depend solely on these reference values when deciding whether a part is faulty or not.

1. DATA LIST FOR OCCUPANT CLASSIFICATION ECU Turn the engine switch off. Connect the Techstream to the DLC3. Turn the engine switch on (IG) and turn the Techstream on. Enter the following menus: Body Electrical / Occupant Detection / Data List. Check the values by referring to the table below. HINT: The Specified Condition for Zero Point Calibration in the table below must be satisfied when the zero point calibration is performed. DATA LIST Tester Display Measurement Item/Range Normal Condition Specified Condition for Zero Point Calibration Diagnostic Note Passenger Classification Passenger classification/ NG: Data is not determined AM50: Adult is seated and seat is in rear position AF05: Adult is seated and seat is in front position CHILD: Child is seated OFF: Vacant AM50/AF05/CHILD/OFF OFF - Passenger Buckle SW Buckle switch (Passenger side)/ Set: Passenger side seat belt is fastened Unset: Passenger side seat belt is unfastened NG: Data is not determined Unset/Set Unset - Pressure Sensor Output Pressure sensor output/ Min.: 0 Max.: 255 0 to 210 0 to 2 - Filtered Pressure Sensor Output Filtered pressure sensor output/ Min.: 0 Max.: 255 38 to 240 38 to 75 If value is outside range of Specified Condition for Zero Point Calibration, check whether any objects placed on seat cushion and that seat cushion fitted correctly. Thermistor Temperature Output Thermistor temperature output/ Min.: -40°C (-40°F) Max.: 90°C (194°F) -40 to 85°C (-40 to 185°F) 3 to 40°C (37 to 104°F) If value is outside range of Specified Condition for Zero Point Calibration, adjust temperature to proper range by using air conditioner, etc. Weight Threshold Weight threshold/ Min.: 0 Max.: 255 36 to 67 (reference value) 36 to 67 (reference value) - Filtered Belt Tension Output Filtered belt tension output/ Min.: 0 Max.: 255 39 to 229 39 to 64 (no load) - Empty Threshold Value from the Seat Factory Empty threshold value from seat factory/ Min.: 0 Max.: 255 38 to 75 38 to 75 - Allow Threshold Threshold value for adult passenger or not from seat factory/ Min.: 0 Max.: 255 43 to 64 (reference value) 43 to 64 (reference value) - Number of Present DTC Number of present trouble codes/ Min.: 0 Max.: 255 0 0 - Number of Past DTC Number of past trouble codes/ Min.: 0 Max.: 255 0 0

DIAGNOSTIC TROUBLE CODE CHART

HINT

When DTC B1650/32 is detected as a result of troubleshooting for the airbag system, perform troubleshooting for the occupant classification system as shown in the chart below.

OCCUPANT CLASSIFICATION SYSTEM

See also:
• HOW TO PROCEED WITH TROUBLESHOOTING
• REMOVAL
• Trouble in Passenger Airbag ON/OFF Indicator
• DIAGNOSTIC TROUBLE CODE CHART
• DTC CHECK / CLEAR
• PROBLEM SYMPTOMS TABLE