DTC B1771: Passenger Side Buckle Switch Circuit Malfunction: Procedure

1. Turn the engine switch on (IG).
2. Clear the DTCs stored in the occupant classification ECU . Refer to DTC CHECK / CLEAR .
3. Clear the DTCs stored in the center airbag sensor assembly . Refer to DTC CHECK / CLEAR .
4. Turn the engine switch off.
5. Turn the engine switch on (IG).
6. Check the DTCs . Refer to DTC CHECK / CLEAR .

   OK

   DTC B1771 is not output.

   HINT: 

   Codes other than 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 engine switch off.
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 PROPERLY, THEN GO TO STEP 1 

OK: Go to next step 

1. Disconnect the connectors from the occupant classification ECU and front seat inner belt assembly RH.
2. Check that the connectors (on the occupant classification ECU side and front seat inner belt assembly RH side) are not damaged.

   OK

   The connectors are not deformed or damaged.

   HINT: 

   If the connectors are not connected securely, reconnect the connectors and proceed to the next inspection.

NG → REPAIR OR REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Connect the negative (-) terminal cable to the battery.
   Fig 1: Checking Front Seat Wire RH (Short To B+)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Turn the engine switch on (IG).
3. Measure the voltage according to the value(s) in the table below.

   Standard voltage

   Tester connection	Condition	Specified condition
   T4-13 (BSW) - Body ground	Engine switch on (IG)	Below 1 V
   T4-14 (BGND) - Body ground	Engine switch on (IG)	Below 1 V

NG → REPAIR OR REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Turn the engine switch off.
   Fig 2: Checking Front Seat Wire RH (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 terminals 1 and 2 of connector C.
   NOTE:

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

4. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester connection	Condition	Specified condition
   T4-13 (BSW) - T4-14 (BGND)	Always	Below 1 Ω

NG → REPAIR OR REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Disconnect the service wire from connector C.
   Fig 3: Checking Front Seat Wire RH (Short To B+)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester connection	Condition	Specified condition
   T4-13 (BSW) - Body ground	Always	1 MΩ or higher
   T4-14 (BGND) - Body ground	Always	1 MΩ or higher

NG → REPAIR OR REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Measure the resistance according to the value(s) in the table below.
   Fig 4: Checking Front Seat Wire RH (Short To B+)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard resistance

   Tester connection	Condition	Specified condition
   T4-13 (BSW) - T4-14 (BGND)	Always	1 MΩ or higher

NG → REPAIR OR REPLACE FRONT SEAT WIRE RH 

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 engine switch on (IG).
4. Clear the DTCs stored in the occupant classification ECU . Refer to DTC CHECK / CLEAR .
5. Clear the DTCs stored in the center airbag sensor assembly . Refer to DTC CHECK / CLEAR
6. Turn the engine switch off.
7. Turn the engine switch on (IG).
8. Check the DTCs . Refer to DTC CHECK / CLEAR .

   OK

   DTC B1771 is not output.

   HINT: 

   Codes other than 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 engine switch off.
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 to REMOVAL .

   HINT: 

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

4. Connect the negative (-) terminal cable to the battery.
5. Turn the engine switch on (IG).
6. Clear the DTCs stored in the occupant classification ECU . Refer to DTC CHECK / CLEAR .
7. Clear the DTCs stored in the center airbag sensor assembly . Refer to DTC CHECK / CLEAR
8. Turn the engine switch off.
9. Turn the engine switch on (IG).
10. Check the DTCs . Refer to DTC CHECK / CLEAR .

    OK

    DTC B1771 is not output.

    HINT: 

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

OK → END 

NG: Go to next step 

1. Connect Techstream to the DLC3.
2. Turn the engine switch on (IG).
3. Using Techstream, save the ECU data from the ECU which has been installed on the vehicle . Refer to REGISTRATION .
4. Turn the engine switch off.
5. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
6. Replace the occupant classification ECU . Refer to REMOVAL .
7. Connect the negative (-) terminal cable to the battery.
8. Turn the engine switch on (IG).
9. Using Techstream, load the previous ECU data stored into the new ECU . Refer to REGISTRATION .
10. Turn the engine switch off.
11. Turn the engine switch on (IG).
12. Clear the DTCs stored in the memory . Refer to DTC CHECK / CLEAR .

    HINT: 

    If DTC is not cleared at this time, past DTC will remain.

NEXT: Go to next step 

1. Perform the sensitivity check . Refer to INITIALIZATION .

NEXT → END