DTC B1771: Passenger Side Buckle Switch Circuit Malfunction: Procedure

WARNING: This page is about a different car, the 2011 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.

CHECK DTC
1. Turn the ignition 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 ignition switch off.
5. Turn the ignition switch on (IG).
6. Check 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.
OK → USE SIMULATION METHOD TO CHECK

NG: Go to next step
CHECK CONNECTION OF CONNECTORS
1. Turn the ignition switch off.
2. Disconnect the negative (-) terminal cable from the battery.
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 connected.
NG → CONNECT CONNECTORS, THEN GO TO STEP 1 1

OK: Go to next step

CHECK FRONT SEAT WIRE RH (SHORT TO B+)

Disconnect the connectors from the occupant classification ECU and the front seat inner belt assembly RH.

Fig 1: Checking Front Seat Wire Terminals RH (Short To B+)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Connect the negative (-) terminal cable to the battery.
Turn the ignition switch on (IG).

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

Standard voltage

Tester connection	Condition	Specified condition
O4-9 (BSW) - Body ground	Ignition switch on (IG)	Below 1 V
O4-5 (BGND) - Body ground	Ignition switch on (IG)	Below 1 V

NG → REPAIR OR REPLACE FRONT SEAT WIRE RH

OK: Go to next step

CHECK FRONT SEAT WIRE RH (OPEN)

Fig 2: Checking Front Seat Wire Terminals RH (Open)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Disconnect the negative (-) terminal cable from the battery.
Using a service wire, connect O3-2 and O3-1 of connector "C".
NOTE:
Do not forcibly insert a service wire into the terminals of the connector when connecting.

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

Standard resistance

Tester connection	Condition	Specified condition
O4-9 (BSW) - O4-5 (BGND)	Always	Below 1 Ω

NG → REPAIR OR REPLACE FRONT SEAT WIRE RH

OK: Go to next step

CHECK FRONT SEAT WIRE RH (SHORT)

Disconnect the service wire from connector "C".

Fig 3: Checking Front Seat Wire Terminals RH (Short)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

Standard resistance

Tester connection	Condition	Specified condition
O4-9 (BSW) - O4-5 (BGND)	Always	1 MΩ or Higher

NG → REPAIR OR REPLACE FRONT SEAT WIRE RH

OK: Go to next step

CHECK FRONT SEAT WIRE RH (SHORT TO GROUND)

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

Fig 4: Checking Front Seat Wire Terminals RH (Short To Ground)

Standard resistance

Tester connection	Condition	Specified condition
O4-9 (BSW) - Body ground	Always	1 MΩ or Higher
O4-5 (BGND) - Body ground	Always	1 MΩ or Higher

NG → REPAIR OR REPLACE FRONT SEAT WIRE RH

OK: Go to next step

CHECK DTC
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 (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 ignition switch off.
7. Turn the ignition switch on (IG).
8. Check 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.
OK → USE SIMULATION METHOD TO CHECK

NG: Go to next step
REPLACE FRONT SEAT INNER BELT ASSEMBLY RH
1. Turn the ignition switch off.
2. Disconnect the negative (-) terminal cable from the battery.
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 ignition 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 ignition switch off.
9. Turn the ignition switch on (IG).
10. Check 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.
OK → END

NG: Go to next step
REPLACE OCCUPANT CLASSIFICATION ECU
1. Turn the ignition switch off.
2. Disconnect the negative (-) terminal cable from the battery.
3. Replace the occupant classification ECU. Refer to REMOVAL .
NEXT: Go to next step
PERFORM ZERO POINT CALIBRATION
1. Connect the negative (-) terminal cable to the battery.
2. Connect the Techstream to the DLC3.
3. Turn the ignition switch on (IG).
4. Using the Techstream, perform "Zero point calibration". Refer to INITIALIZATION .
  OK
  
  The "Zero Point Calibration is complete." is displayed.
NEXT: Go to next step
PERFORM SENSITIVITY CHECK
1. Using the Techstream, perform "Sensitivity check". Refer to INITIALIZATION .
  Standard value
  
  27 to 33 kg (59.52 to 72.75 lb)
NEXT → END