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. Refer to DTC CHECK / CLEAR .
4. Turn the engine switch off.
5. Turn the engine switch on (IG).
6. 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   2 

OK → See step   10 

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

Fig 1: Identifying Front Seat Inner Belt Connector Terminal C35, C33 And Occupant Classification ECU Connector Terminal C8

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
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
   c8-13 (BSW) - Body ground	Engine switch on (IG)	Below 1 V
   c8-14 (BGND) - Body ground

4. Turn the engine switch off.
5. Disconnect the cable from the negative (-) battery terminal, 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 a service wire.

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

   Standard Resistance

   Tester Connection	Condition	Specified condition
   c8-13 (BSW) - c8-14 (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
   c8-13 (BSW) - Body ground	Always	1 MΩ or higher
   c8-14 (BGND) - Body ground
   c8-13 (BSW) - c8-14 (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 cable to the negative (-) battery terminal, and wait for at least 2 seconds.
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. 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 DTC B1771 may be output at this time, but they are not related to this check.

NG → See step   6 

OK → See step   10 

1. Turn the engine switch off.
2. Disconnect the cable from the negative (-) battery terminal, 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 cable to the negative (-) battery terminal, and wait for at least 2 seconds.
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. 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 DTC B1771 may be output at this time, but they are not related to this check.

NG → See step   7 

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 which is installed in the vehicle. Refer to REGISTRATION .
4. Turn the engine switch off.
5. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
6. Replace the No. 1 seat cushion (occupant classification ECU). Refer to DISASSEMBLY .
7. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
8. Turn the engine switch on (IG).
9. Using the Techstream, load the previous ECU data stored in the Techstream 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 DTCs are not cleared at this time, past DTCs will remain.

NEXT: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG).
3. Using the Techstream, perform zero point calibration. Refer to INITIALIZATION .
4. Turn the engine switch off.
5. Turn the engine switch on (IG).
6. Clear the DTCs stored in the occupant classification ECU. Refer to DTC CHECK / CLEAR .

   HINT: 

   If the DTCs are not cleared at this time, past DTCs will remain.

NEXT: Go to next step 

1. Perform the sensitivity check. Refer to INITIALIZATION .

NEXT → END