DTC B1771: Passenger Side Buckle Switch Circuit Malfunction: Procedure

1. Turn the power switch off.
2. Disconnect the cable from the negative (-) auxiliary battery terminal.
3. Check that the connectors are properly connected to the occupant detection ECU and 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 detection ECU and 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 (-) auxiliary battery terminal.
   Fig 1: Checking Front Seat Wire RH For Short To B+

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   W3-9 (BSW) - Body ground	Power switch on (IG)	Below 1 V
   W3-5 (BGND) - Body ground	Power switch on (IG)	Below 1 V

4. Turn the power switch off.
5. Disconnect the cable from the negative (-) auxiliary battery terminal.
   TEXT IN ILLUSTRATION
   
   

   *1	Front Seat Inner Belt Assembly RH
   *2	Occupant Detection ECU
   *3	Front Seat Wire RH
   *a	Front view of wire harness connector (to Occupant Detection ECU)

NG → REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Using a service wire, connect terminals 1 (BSW) and 2 (BGND) of connector C.
   Fig 2: Check For Open In Front Seat Wire RH

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   NOTE:

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

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   W3-9 (BSW) - W3-5 (BGND)	Always	Below 1 Ω

3. Disconnect the service wire from connector C.
   TEXT IN ILLUSTRATION
   
   

   *1	Front Seat Inner Belt Assembly RH
   *2	Occupant Detection ECU
   *3	Front Seat Wire RH
   *4	Service Wire
   *a	Front view of wire harness connector (to Occupant Detection ECU)
   *b	Front view of wire harness connector (to Front Seat Inner Belt Assembly RH)

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 3: Checking Front Seat Wire RH For Short

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   W3-9 (BSW) - W3-5 (BGND)	Always	1 MΩ or higher

   TEXT IN ILLUSTRATION
   
   

   *1	Front Seat Inner Belt Assembly RH
   *2	Occupant Detection ECU
   *3	Front Seat Wire RH
   *a	Front view of wire harness connector (to Occupant Detection ECU)

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 Short To Ground

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   W3-9 (BSW) - Body ground	Always	1 MΩ or higher
   W3-5 (BGND) - Body ground	Always	1 MΩ or higher

   TEXT IN ILLUSTRATION
   
   

   *1	Front Seat Inner Belt Assembly RH
   *2	Occupant Detection ECU
   *3	Front Seat Wire RH
   *a	Front view of wire harness connector (to Occupant Detection ECU)

NG → REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Connect the connectors to the occupant detection ECU and front seat inner belt assembly RH.
2. Connect the cable to the negative (-) auxiliary battery terminal.
3. Clear the DTCs stored in the occupant detection ECU. Refer to DTC CHECK / CLEAR .
4. Clear the DTCs stored in the airbag ECU assembly. Refer to DTC CHECK / CLEAR .
5. Turn the power switch off.
6. Turn the power switch on (IG).
7. 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.

8. Turn the power switch off.

NG → See step   7 

OK → See step   11 

1. Disconnect the cable from the negative (-) auxiliary battery terminal.
2. Replace the front seat inner belt assembly RH with a known good one. Refer to REMOVAL .

   HINT: 

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

3. Connect the cable to the negative (-) auxiliary battery terminal.
4. Clear the DTCs stored in the occupant detection ECU. Refer to DTC CHECK / CLEAR .
5. Clear the DTCs stored in the airbag ECU assembly. Refer to DTC CHECK / CLEAR .
6. Turn the power switch off.
7. Turn the power 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.

9. Turn the power switch off.
10. Disconnect the cable from the negative (-) auxiliary battery terminal.
11. Return the front seat inner belt assembly RH that was installed for testing to its original location. Refer to REMOVAL .

NG → See step   8 

OK → See step   12 

1. Disconnect the cable from the negative (-) auxiliary battery terminal.
2. Replace the occupant detection ECU with a new one. Refer to REMOVAL .
3. Connect the cable to the negative (-) auxiliary battery terminal.

NEXT: Go to next step 

1. Using the Techstream, perform Zero Point Calibration. Refer to INITIALIZATION .

NEXT: Go to next step 

1. Using the Techstream, perform Sensitivity Check. Refer to INITIALIZATION .

NEXT → END