DTC B1771: Passenger Side Buckle Switch Circuit Malfunction: Procedure

1. Turn the engine switch off.
2. Disconnect the cable from the negative (-) battery terminal.
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.

   HINT: 

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

4. Disconnect the connectors from the occupant classification ECU and the front seat inner belt assembly RH.
5. Check that the terminals of the connectors are not damaged.

   OK

   The terminals are not deformed or damaged.

NG → REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

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

   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	Switch Condition	Specified condition
   T16-13 (BSW) - Body ground	Engine switch on (IG)	Below 1 V
   T16-14 (BGND) - Body ground	Engine switch on (IG)	Below 1 V

NG → REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Turn the engine switch off.
   Fig 2: Checking Front Seat Wire RH For An Open

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect the cable from the negative (-) battery terminal.
3. Using SST, connect terminals 1 (RBE-) and 2 (RBE+) of connector C.
   NOTE:

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

   • SST: 09843-18040 
4. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester connection	Condition	Specified condition
   T16-13 (BSW) - T16-14 (BGND)	Always	Below 1 Ω

NG → REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Disconnect SST from connector C.
   Fig 3: Checking Front Seat Wire RH For A Short

   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
   T16-13 (BSW) - Body ground	Always	1 MΩ or higher
   T16-14 (BGND) - Body ground	Always	1 MΩ or higher

NG → 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 For A Short

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

   Tester connection	Condition	Specified condition
   T16-13 (BSW) - T16-14 (BGND)	Always	1 MΩ or higher

NG → 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 cable to the negative (-) battery terminal.
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 for 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.

NG → See step   7 

OK → See step   10 

1. Turn the engine switch off.
2. Disconnect the cable from the negative (-) battery terminal.
3. Replace the front seat inner belt assembly RH with a known good part. Refer to REMOVAL .

   HINT: 

   Perform an inspection using known good parts from another vehicle if possible.

4. Connect the cable to the negative (-) battery terminal.
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 for 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.

NG → See step   8 

OK → END 

1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG).
3. Using the Techstream, save the ECU data from the ECU currently installed on the vehicle. Refer to REGISTRATION .
4. Turn the engine switch off.
5. Disconnect the cable from the negative (-) battery terminal.
6. Replace the occupant classification ECU. Refer to REMOVAL .
7. Connect the cable to the negative (-) battery terminal.
8. Turn the engine switch on (IG).
9. Using the 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 the DTCs are not cleared at this time, past DTC will remain.

NEXT: Go to next step 

1. Perform the sensitivity check. Refer to INITIALIZATION .

NEXT → END