B1771

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

DTC B1771 - Passenger Side Buckle Switch Circuit Malfunction

DESCRIPTION

The passenger side buckle switch circuit consists of the occupant classification ECU and the front seat inner belt RH.
DTC B1771 is recorded 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 detected as a result of troubleshooting the airbag system, perform troubleshooting for DTC B1771 of the occupant classification system.
- Use a Techstream to check for DTCs of the occupant classification ECU, otherwise the DTC cannot be read.

WIRING DIAGRAM





INSPECTION PROCEDURE
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 ON, and wait for at least 60 seconds.
(b) Clear the DTCs stored in the memory .
HINT: First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor.
(c) Turn the ignition switch off.
(d) Turn the ignition switch ON, and wait for at least 60 seconds.
(e) Check for DTCs.
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
2. CHECK CONNECTION OF CONNECTOR
(a) Turn the ignition switch off.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) 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 CONNECTOR
OK -- Continue to next step.
3. CHECK CONNECTOR
(a) Disconnect the connectors from the occupant classification ECU and the front seat inner belt RH.
(b) Check that the connectors (on the occupant classification ECU side and passenger side buckle switch side) are not damaged Electronic Circuit Inspection Procedure.
OK:
Connectors are not deformed or damaged.
NG -- REPLACE FRONT SEAT WIRE RH
OK -- Continue to next step.
4. CHECK FRONT SEAT WIRE RH





(a) Connect the negative (-) terminal cable to the battery, and wait for at least 2 seconds.
(b) Turn the ignition switch ON, and wait for at least 60 seconds.
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:





(d) Turn the ignition switch off.
(e) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(f) 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.
(g) Measure the resistance according to the value(s) in the table below.
Standard resistance:





(h) Disconnect the service wire from connector C.
(i) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPLACE FRONT SEAT WIRE RH
OK -- Continue to next step.
5. CHECK FOR DTC
(a) Connect the connectors to the occupant classification ECU and the front seat inner belt RH.
(b) Connect the negative (-) terminal cable to the battery, and wait for at least 2 seconds.
(c) Turn the ignition switch ON, and wait for at least 60 seconds.
(d) Clear the DTCs stored in the memory .
HINT: First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor.
(e) Turn the ignition switch off.
(f) Turn the ignition switch ON, and wait for at least 60 seconds.
(g) Check for DTCs .
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
6. REPLACE FRONT SEAT INNER BELT ASSEMBLY RH
(a) Turn the ignition switch off.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Replace the front seat inner belt RH .
HINT: Perform the inspection using parts from a normal vehicle when possible.
(d) Connect the negative (-) terminal cable to the battery, and wait for at least 2 seconds.
NEXT -- Continue to next step.
7. CHECK FOR DTC
(a) Turn the ignition switch ON, and wait for at least 60 seconds.
(b) Clear the DTCs stored in the memory .
HINT: First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor.
(c) Turn the ignition switch off.
(d) Turn the ignition switch ON, and wait for at least 60 seconds.
(e) Check for DTCs .
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
8. REPLACE OCCUPANT CLASSIFICATION ECU
(a) Turn the ignition switch off.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Replace the occupant classification ECU .
HINT: Perform the inspection using parts from a normal vehicle when possible.
(d) Connect the negative (-) terminal cable to the battery, and wait for at least 2 seconds.
(e) Turn the ignition switch ON, and wait for at least 60 seconds.
(f) Clear the DTCs stored in the memory .
HINT: If the DTCs are not cleared at this time, past DTCs will remain.

NEXT -- Continue to next step.
9. PERFORM ZERO POINT CALIBRATION
(a) Connect a Techstream to the DLC3.
(b) Turn the ignition switch ON, and wait for at least 60 seconds.
(c) Using the Techstream, perform the zero point calibration .
NEXT -- Continue to next step.
10. PERFORM SENSITIVITY CHECK
(a) Using a Techstream, perform the sensitivity check .
Standard range:
27 to 33 kg (59.5 to 72.8 lb)
NEXT -- END