B1771

SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: B1771: Passenger Side Buckle Switch Circuit Malfunction
B1771 - Passenger Side Buckle Switch Circuit Malfunction

DESCRIPTION

The passenger side buckle switch circuit consists of the occupant classification ECU and front seat inner belt RH.

DTC B1771 is stored when a malfunction is detected in the passenger side buckle switch circuit.

Troubleshoot DTC B1771 first when DTCs B1771 and B1795 are output simultaneously.





HINT
* When DTC B1650/32 is stored as a result of troubleshooting the airbag system, perform troubleshooting for DTC B1771 of the occupant classification system.
* Use the Techstream to check for DTCs of the occupant classification ECU, otherwise the DTCs cannot be read.

WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
When disconnecting the cable, some systems need to be initialized after the cable is reconnected Repair Instruction - Initialization.

HINT
* If troubleshooting (wire harness inspection) is difficult to perform, remove the front seat RH installation bolts to see the undersurface of the seat cushion.
* In the above case, hold the seat so that it does not fall down. Holding the seat for a long period of time may cause a problem, such as seat rail deformation. Hold the seat up only for as long as necessary.

PROCEDURE

1. CHECK FOR DTC

(a) Turn the ignition switch to ON, and wait for at least 60 seconds.

(b) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.

HINT
First clear the DTCs stored in the occupant classification ECU, and then clear the DTCs stored in the center airbag sensor.

(c) Turn the ignition switch off.

(d) Turn the ignition switch to ON, and wait for at least 60 seconds.

(e) Check for DTCs Reading and Clearing Diagnostic Trouble Codes.

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 -- CHECK CONNECTION OF CONNECTOR

OK -- USE SIMULATION METHOD TO CHECK Diagnosis System

2. CHECK CONNECTION OF CONNECTOR

(a) Turn the ignition switch off.

(b) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.

(c) Check that the connectors are properly connected to the occupant classification ECU and front seat inner belt RH.

OK:

Connectors are properly connected.

NG -- CONNECT CONNECTOR
OK -- Continue to next step.

3. CHECK CONNECTOR

(a) Disconnect the connectors from the occupant classification ECU and front seat inner belt RH.

(b) Check that the connectors (on the occupant classification ECU side and front passenger side buckle switch side) are not damaged.

OK:

Connectors are not deformed or damaged.

NG -- REPLACE FRONT SEAT WIRE RH Disassembly
OK -- Continue to next step.

4. CHECK FRONT SEAT WIRE RH (FRONT SEAT INNER BELT RH - OCCUPANT CLASSIFICATION ECU)

(a) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.





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

Standard Voltage:





(c) Turn the ignition switch off.

(d) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.

(e) Using a service wire, connect terminals 1 (RBE+) and 2 (RBE-) of connector C.

NOTICE:
Do not forcibly insert the service wire into the terminals of the connector.

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

Standard Resistance:





(g) Disconnect the service wire from connector C.

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

Standard Resistance:





Text in Illustration





NG -- REPLACE FRONT SEAT WIRE RH Disassembly
OK -- Continue to next step.

5. CHECK FOR DTC

(a) Connect the connectors to the occupant classification ECU and front seat inner belt RH.

(b) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.

(c) Turn the ignition switch to ON, and wait for at least 60 seconds.

(d) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.

HINT
First clear the DTCs stored in the occupant classification ECU, and then clear the DTCs stored in the center airbag sensor.

(e) Turn the ignition switch off.

(f) Turn the ignition switch to ON, and wait for at least 60 seconds.

(g) Check for DTCs Reading and Clearing Diagnostic Trouble Codes.

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 -- REPLACE FRONT SEAT INNER BELT ASSEMBLY RH

OK -- USE SIMULATION METHOD TO CHECK Diagnosis System

6. REPLACE FRONT SEAT INNER BELT ASSEMBLY RH

(a) Turn the ignition switch off.

(b) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.

(c) Replace the front seat inner belt RH Removal.

HINT
Perform the inspection using parts from a normal vehicle when possible.

(d) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.

(e) Turn the ignition switch to ON, and wait for at least 60 seconds.

(f) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.

HINT
First clear the DTCs stored in the occupant classification ECU, and then clear the DTCs stored in the center airbag sensor.

(g) Turn the ignition switch off.

(h) Turn the ignition switch to ON, and wait for at least 60 seconds.

(i) Check for DTCs Reading and Clearing Diagnostic Trouble Codes.

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 -- REPLACE OCCUPANT CLASSIFICATION ECU

OK -- END (FRONT SEAT INNER BELT RH IS DEFECTIVE)

7. REPLACE OCCUPANT CLASSIFICATION ECU

(a) Turn the ignition switch off.

(b) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.

(c) Replace the occupant classification ECU Removal.

HINT
Perform the inspection using parts from a normal vehicle when possible.

(d) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.

(e) Turn the ignition switch to ON, and wait for at least 60 seconds.

(f) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.

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

NEXT -- Continue to next step.

8. PERFORM ZERO POINT CALIBRATION

(a) Perform the zero point calibration Programming and Relearning.

OK:

"Zero Point Calibration is complete." is displayed.

NEXT -- Continue to next step.

9. PERFORM SENSITIVITY CHECK

(a) Perform the sensitivity check Programming and Relearning.

Standard:

27 to 33 kg (59.5 to 72.8 lb)

NEXT -- END (OCCUPANT CLASSIFICATION ECU IS DEFECTIVE)