DTC B1771: Passenger Side Buckle Switch Circuit Malfunction: Procedure

1. Turn the ignition switch to 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 DTC CHECK / CLEAR .
4. Turn the ignition switch to OFF.
5. Turn the ignition switch to 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.

NG → See step   2 

OK → See step   14 

1. Turn the ignition switch to 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 occupant classification ECU side and front seat inner belt RH side) 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 → 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

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

   Standard voltage

   Tester Connection	Switch Condition	Specified condition
   M2-13 (BSW) - Body ground	Ignition switch ON	Below 1 V
   M2-14 (BGND) - Body ground

4. Turn the ignition switch to OFF.
5. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
6. Using a service wire, connect terminals 1 (RBE+) and 2 (RBE-) 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
   M2-13 (BSW) - M2-14 (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
   M2-13 (BSW) - Body ground	Always	1 MΩ or higher
   M2-14 (BGND) - Body ground
   M2-13 (BSW) - M2-14 (BGND)

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 RH.
2. Connect the negative (-) terminal cable to the battery.
3. Turn the ignition switch to 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 DTC CHECK / CLEAR .
6. Turn the ignition switch to OFF.
7. Turn the ignition switch to ON.
8. Check for the DTCs. Refer to DTC 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.

NG → See step   6 

OK → See step   14 

1. Turn the ignition switch to 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.

NEXT: Go to next step 

1. Turn the ignition switch to 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 DTC CHECK / CLEAR .
4. Turn the ignition switch to OFF.
5. Turn the ignition switch to ON.
6. Check for the DTCs. Refer to DTC 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.

NG → See step   8 

OK → END 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Using the Techstream, save the ECU data from the ECU which was installed on the vehicle. Refer to REGISTRATION .

NEXT: Go to next step 

1. Turn the ignition switch to OFF.
2. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
3. Replace the occupant classification ECU. Refer to REMOVAL .
4. Connect the negative (-) terminal cable to the battery.

NEXT: Go to next step 

1. Turn the ignition switch to ON.
2. Using the Techstream, load the previous ECU data stored in the tester into the new ECU. Refer to REGISTRATION .

NEXT: Go to next step 

1. Using the Techstream, perform zero point calibration. Refer to INITIALIZATION .

NEXT: Go to next step 

HINT: 

Check that the zero point calibration is completed normally. If one of the following conditions is met, DTC B1797 will be output (refer to INITIALIZATION. Refer to INITIALIZATION ):

• Zero point calibration is performed when the conditions for the calibration are not satisfied.
• Zero point calibration has failed.

1. Clear the DTCs stored in the occupant classification ECU. Refer to DTC CHECK / CLEAR .
2. Clear the DTCs stored in the center airbag sensor. Refer to DTC CHECK / CLEAR .
3. Turn the ignition switch to OFF.
4. Turn the ignition switch to ON.
5. Check for the DTCs. Refer to DTC CHECK / CLEAR .

   OK

   DTC B1797 is not output.

NG → See step   15 

OK: Go to next step 

1. Perform the sensitivity check. Refer to INITIALIZATION .

NEXT → END