DTC B1771: Passenger Side Buckle Switch Circuit Malfunction: Procedure

1. Turn the ignition switch ON.
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. Refer to REMOVAL .
4. Turn the ignition switch OFF.
5. Turn the ignition switch ON.
6. Check for 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   9 

NG: Go to next step 

1. Turn the ignition 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 RH.

   OK

   Connectors are properly connected.

NG → CONNECT CONNECTORS PROPERLY 

OK: Go to next step 

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

   OK

   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: Front Seat Wire Connector Terminals

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

   Standard voltage

   Tester connection	Switch Condition	Specified condition
   O3-13 (BSW) - Body ground	Ignition switch ON	Below 1 V
   O3-14 (BGND) - Body ground

4. Turn the ignition switch OFF.
5. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
6. Using a service wire, connect terminals 3 and 7 of connector C.
   NOTE:

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

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

   Standard resistance

   Tester connection	Condition	Specified condition
   O3-13 (BSW) - O3 -14 (BGND)	Always	Below 1 Ω

8. Disconnect the service wire from connector C.
9. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester connection	Condition	Specified condition
   O3-13 (BSW) - Body ground	Always	1 MΩ or higher
   O3-14 (BGND) - Body ground
   O3-13 (BSW) - O3-14 (BGND)

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 ignition switch ON.
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. Refer to REMOVAL
6. Turn the ignition switch OFF.
7. Turn the ignition switch ON.
8. Check for 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   9 

NG: Go to next step 

1. Turn the ignition 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 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 ignition switch ON.
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. Refer to DTC CHECK / CLEAR
8. Turn the ignition switch OFF.
9. Turn the ignition switch ON.
10. Check for 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 the Techstream to the DLC3.
2. Turn the ignition switch ON.
3. Using the Techstream, save the ECU data from the ECU which has been installed on the vehicle. Refer to REGISTRATION .
4. Turn the ignition 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 DISASSEMBLY .
7. Connect the negative (-) terminal cable to the battery.
8. Turn the ignition switch ON.
9. Using the Techstream, load the previous ECU data stored into the new ECU. Refer to REGISTRATION .
10. Turn the Ignition switch OFF.
11. Turn the ignition switch ON.
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