DTC B1771: Passenger Side Buckle Switch Circuit Malfunction: Procedure

1. Turn the ignition switch to the on position.
2. Clear the DTCs stored in the memory. Refer toDTC 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. Refer toDTC CHECK / CLEAR .

   OK

   DTC B1771 is not output.

   HINT: 

   Codes other than DTC B1771 may be output at this time, but they are not related to this check.

OK → See step   12 

NG: Go to next step 

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 front seat inner belt assembly RH.

   OK

   The connectors are properly connected.

NG → CONNECT CONNECTORS 

OK: Go to next step 

1. Disconnect the connectors from the occupant classification ECU and the front seat inner belt assembly RH.
   Fig 1: Identifying Front Seat Inner Belt Assembly RH & No. 1 Seat Wire (For Short)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Connect the negative (-) terminal cable to the battery.
3. Turn the ignition switch to the on position.
4. Measure the voltage.

   Standard voltage

   Tester connection	Condition	Specified condition
   Q4-9 (BSW) - Body ground	Ignition switch on	Below 1 V
   Q4-5 (BGND) - Body ground	Ignition switch on	Below 1 V

NG → REPAIR OR REPLACE NO. 1 SEAT WIRE 

OK: Go to next step 

1. Turn the ignition switch to the lock position.
   Fig 2: Identifying Q3 - 2 & Q 3 - 1 Connector C, Front Seat Inner Belt Assembly RH & No. 1 Seat Wire (For Open)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
3. Using a service wire, connect Q3-2 and Q3-1 of connector C.
   NOTE:

   Do not forcibly insert a service wire into the terminals of the connector when connecting.

4. Measure the resistance.

   Standard resistance

   Tester connection	Condition	Specified condition
   Q4-9 (BSW) - Q4-5 (BGND)	Always	Below 1 Ω

NG → REPAIR OR REPLACE NO. 1 SEAT WIRE 

OK: Go to next step 

1. Disconnect the service wire from connector C.
   Fig 3: Identifying Front Seat Inner Belt Assembly RH & No. 1 Seat Wire (For Short)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance.

   Standard resistance

   Tester connection	Condition	Specified condition
   Q4-9 (BSW) - Q4-5 (BGND)	Always	1 MΩ or higher

NG → REPAIR OR REPLACE NO. 1 SEAT WIRE 

OK: Go to next step 

1. Measure the resistance.
   Fig 4: Identifying Front Seat Inner Belt Assembly RH & No. 1 Seat Wire (For Short)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard resistance

   Tester connection	Condition	Specified condition
   Q4-9 (BSW) - Body ground	Always	1 MΩ or higher
   Q4-5 (BGND) - Body ground	Always	1 MΩ or higher

NG → REPAIR OR REPLACE NO. 1 SEAT WIRE 

OK: Go to next step 

1. Connect the connectors to the occupant classification ECU and the front seat inner belt assembly RH.
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. Refer toDTC 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. Refer toDTC CHECK / CLEAR .

   OK

   DTC B1771 is not output.

   HINT: 

   Codes other than DTC B1771 may be output at this time, but they are not related to this check.

OK → See step   12 

NG: Go to next step 

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 inner belt assembly RH. Refer toREMOVAL .

   HINT: 

   Perform the inspection using parts from a normal vehicle if possible.

4. Connect the negative (-) terminal cable to the battery.
5. Turn the ignition switch to the on position.
6. Clear the DTCs stored in the memory. Refer toDTC CHECK / CLEAR .

   HINT: 

   First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.

7. Turn the ignition switch to the lock position.
8. Turn the ignition switch to the on position.
9. Check the DTCs. Refer toDTC CHECK / CLEAR .

   OK

   DTC B1771 is not output.

   HINT: 

   Codes other than DTC B1771 may be output at this time, but they are not related to this check.

OK → END 

NG: Go to next step 

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. Refer toREMOVAL .

NEXT: Go to next step 

1. Connect the negative (-) terminal cable to the battery.
2. Connect a Techstream to the DLC3.
3. Turn the ignition switch to the on position.
4. Using the Techstream, perform the zero point calibration. Refer toINITIALIZATION .

   OK

   COMPLETED is displayed on the tester.

NEXT: Go to next step 

1. Using a Techstream, perform the sensitivity check. Refer toINITIALIZATION .
   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).

NEXT → END