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HOMESERVICE MANUALSTOYOTA2009YARIS S, 4D HATCHBACKREPAIR AND DIAGNOSISRESTRAINTSAIR BAG, SRSSUPPLEMENTAL RESTRAINT SYSTEMOCCUPANT CLASSIFICATION SYSTEMDTC B1793 OCCUPANT CLASSIFICATION SENSOR POWER SUPPLY CIRCUIT MALFUNCTIONINSPECTION PROCEDURE

2009 Toyota Yaris S, 4D Hatchback

Inspection Procedure

2009 Toyota Yaris S, 4D HatchbackSECTION Inspection Procedure

HINT:

If troubleshooting (wire harness inspection) is difficult to perform, remove the front passenger seat installation bolts to see the under surface of the seat cushion.
In the above case, hold the seat so that it does not tip over. Holding the seat for a long period of time may cause a problem, such as seat rail deformation. Hold the seat up only for as long as necessary.

CHECK DTC
1. Turn the ignition switch to the on position.
2. Clear the DTCs stored in the memory (See DTC CHECK/CLEAR ).
  HINT:
  
  First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.
3. Turn the ignition switch to the lock position.
4. Turn the ignition switch to the on position.
5. Check the DTCs (See DTC CHECK/CLEAR ).
  OK: DTC B1793 is not output.
  
  HINT:
  
  Codes other than DTC B1793 may be output at this time, but they are not related to this check.
OK: USE SIMULATION METHOD TO CHECK

NG: GO TO NEXT STEP
CHECK CONNECTION OF CONNECTORS
1. Turn the ignition switch to the lock position.
2. Disconnect the negative (-) terminal cable from the battery and wait for at least 90 seconds.
3. Check that the connectors are properly connected to the occupant classification ECU and the occupant classification sensors.
  OK: The connectors are properly connected.
NG: CONNECT CONNECTORS

OK: GO TO NEXT STEP

CHECK FRONT SEAT WIRE RH (TO B+)

Disconnect the connectors from the occupant classification ECU and the 4 occupant classification sensors.
Connect the negative (-) terminal cable to the battery.
Turn the ignition switch to the on position.

Measure the voltage.

Standard voltage

TESTER CONNECTION SPECIFIED CONDITION

Tester connection	Condition	Specified condition
04-11 (SVC1) - Body ground	Ignition switch on	Below 1 V
04-12 (SVC2) - Body ground	Ignition switch on	Below 1V
04-5 (SVC3) - Body ground	Ignition switch on	Below IV
04-6 (SVC4) - Body ground	Ignition switch on	Below 1 V

Fig 1: Checking Front Seat Wire RH (To B+)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG: REPAIR OR REPLACE FRONT SEAT WIRE RH

OK: GO TO NEXT STEP

CHECK FRONT SEAT WIRE RH (TO GROUND)

Turn the ignition switch to the lock position.
Disconnect the negative (-) terminal cable from the battery and wait for at least 90 seconds.

Measure the resistance.

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION

Tester connection	Condition	Specified condition
04-11 (SVC1) - Body ground	Always	1 MΩ or higher
04-12 (SVC2) - Body ground	Always	1 MΩ or higher
04-5 (SVC3) - Body ground	Always	1 MΩ or higher
O4-6 (SVC4) - Body ground	Always	1 MΩ or higher

Fig 2: Checking Front Seat Wire RH (To B+)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG: REPAIR OR REPLACE FRONT SEAT WIRE RH

OK: GO TO NEXT STEP

CHECK FRONT SEAT WIRE RH (FOR OPEN)

Measure the resistance.

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION

Tester connection	Condition	Specified condition
04-11 (SVC1)-05-1 (SVC1)	Always	Below 1 Ω
04-12 (SVC2)-06-1 (SVC2)	Always	Below 1 Ω
04-5 (SVC3)-07-1 (SVC3)	Always	Below 1 Ω
04-6 (SVC4)-08-1 (SVC4)	Always	Below 1 Ω

Fig 3: Checking Front Seat Wire RH (For Open)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG: REPAIR OR REPLACE FRONT SEAT WIRE RH

OK: GO TO NEXT STEP

CHECK FRONT SEAT WIRE RH (FOR SHORT)

Measure the resistance.

Fig 4: Checking Front Seat Wire RH (To B+)

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION

Tester connection	Condition	Specified condition
04-5 (SVC3) -04-6 (SVC4)	Always	1 MΩ or higher
O4-6 (SVC4) -O4-11 (SVC1)	Always	1 MΩ or higher
04-11 (SVC1) -04-12 (SVC2)	Always	1 MΩ or higher
04-12 (SVC2) -04-5 (SVC3)	Always	1 MΩ or higher
04-12 (SVC2) -04-6 (SVC4)	Always	1 MΩ or higher
04-11 (SVC1)-04-5 (SVC3)	Always	1 MΩ or higher

NG: REPAIR OR REPLACE FRONT SEAT WIRE RH

OK: GO TO NEXT STEP

CHECK DTC
1. Connect the connectors to the occupant classification ECU and the 4 occupant classification sensors.
2. Connect the negative (-) terminal cable to the battery.
3. Turn the ignition switch to the on position.
4. Clear the DTCs stored in the memory (See DTC CHECK/CLEAR ).
  HINT:
  
  First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.
5. Turn the ignition switch to the lock position.
6. Turn the ignition switch to the on position.
7. Check the DTCs (See DTC CHECK/CLEAR ).
  OK: DTC B1793 is not output.
  
  HINT:
  
  Codes other than DTC B1793 may be output at this time, but they are not related to this check.
OK: USE SIMULATION METHOD TO CHECK

NG: GO TO NEXT STEP
REPLACE OCCUPANT CLASSIFICATION ECU
1. Turn the ignition switch to the lock position.
2. Disconnect the negative (-) terminal cable from the battery and wait for at least 90 seconds.
3. Replace the occupant classification ECU (See ON-VEHICLE INSPECTION ).
  HINT:
  
  Perform the inspection using parts from a normal vehicle if possible.
PERFORM ZERO POINT CALIBRATION
1. Connect the negative (-) terminal cable to the battery.
2. Connect the Techstream to the DLC3.
3. Turn the ignition switch to the on position.
4. Using the Techstream, perform the zero point calibration (See INITIALIZATION ).
  OK: COMPLETED is displayed.
NG: Go to step 12

OK: GO TO NEXT STEP
PERFORM SENSITIVITY CHECK
1. Using the Techstream, perform the sensitivity check (See INITIALIZATION ).
  1. Confirm that nothing is placed on the passenger seat.
  2. Confirm that the beginning sensor reading is within the standard range.
    Standard range: -3.2 to 3.2 kg (-7 to 7 lb)
  3. Place a 30 kg (66.14 lb) weight (e.g. a lead mass) onto the front passenger seat.
  4. Confirm that the sensitivity is within the standard range.
    Standard range: 27 to 33 kg (59.52 to 72.75 lb)
    
    HINT:
    
    When performing the sensitivity check, use a solid metal weight (the check result may not be accurate if a liquid weight is used).
NG: Go to step 12

OK: GO TO NEXT STEP
CHECK DTC
1. Connect the negative (-) terminal cable to the battery.
2. Turn the ignition switch to the on position.
3. Clear the DTCs stored in the memory (See DTC CHECK/CLEAR ).
  HINT:
  
  First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.
4. Turn the ignition switch to the lock position.
5. Turn the ignition switch to the on position.
6. Check the DTCs (See DTC CHECK/CLEAR ).
  OK:: DTC B1793 is not output.
  
  HINT:
  
  Codes other than DTC B1793 may be output at this time, but they are not related to this check.
OK: END

NG: GO TO NEXT STEP
REPLACE FRONT SEAT ASSEMBLY RH
1. Turn the ignition switch to the lock position.
2. Disconnect the negative (-) terminal cable from the battery and wait for at least 90 seconds.
3. Replace the front seat assembly RH.
  for Hatchback: REMOVAL
  
  for Sedan: REMOVAL
PERFORM ZERO POINT CALIBRATION
1. Connect the negative (-) terminal cable to the battery.
2. Connect the Techstream to the DLC3.
3. Turn the ignition switch to the on position.
4. Using the Techstream, perform the zero point calibration (See INITIALIZATION ).
  OK: COMPLETED is displayed.
PERFORM SENSITIVITY CHECK
1. Using the Techstream, perform the sensitivity check (See DTC CHECK/CLEAR ).
  1. Confirm that nothing is placed on the passenger seat.
  2. Confirm that the beginning sensor reading is within the standard range.
    Standard range: -3.2 to 3.2 kg (-7 to 7 lb)
  3. Place a 30 kg (66.14 lb) weight (e.g. a lead mass) onto the front passenger seat.
  4. Confirm that the sensitivity is within the standard range.
    Standard range: 27 to 33 kg (59.52 to 72.75 lb)
    
    HINT:
    
    When performing the sensitivity check, use a solid metal weight (the check result may not be accurate if a liquid weight is used).

RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.