B1781

SUPPLEMENTAL RESTRAINT SYSTEM: OCCUPANT CLASSIFICATION SYSTEM: B1781: Front Occupant Classification Sensor RH Circuit Malfunction
B1781 - Front Occupant Classification Sensor RH Circuit Malfunction

DESCRIPTION

The front occupant classification sensor RH circuit consists of the occupant classification ECU and the front occupant classification sensor RH.

DTC B1781 is recorded when a malfunction is detected in the front occupant classification sensor RH circuit.





WIRING DIAGRAM





INSPECTION PROCEDURE

HINT
- If troubleshooting (wire harness inspection) is difficult to perform, remove the front passenger seat installation bolts to see the undersurface of the seat cushion.
- In the above case, hold the seat so that it does not tip over. 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.

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

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 to ON.

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

OK:

DTC B1781 is not output.

HINT
DTCs other than DTC B1781 may be output at this time, but they are not related to this check.

OK -- USE SIMULATION METHOD TO CHECK
NG -- Continue to next step.

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 the front occupant classification sensor RH.

OK:

The connectors are properly connected.

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

3. CHECK FRONT SEAT WIRE RH (TO B+)

(a) Disconnect the connectors from the occupant classification ECU and the front occupant classification sensor RH.





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

(c) Turn the ignition switch to ON.

(d) Measure the voltage of the wire harness side connector.

Standard voltage:





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

4. CHECK FRONT SEAT WIRE RH (FOR OPEN)

(a) Turn the ignition switch off.





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

(c) Using a service wire, connect terminals a4-1 (SVC2) and a4-3 (SGD2), and connect terminals a4-2 (SIG2) and a4-3 (SGD2) of connector C.

NOTICE:
Do not forcibly insert a service wire into the terminals of the connector when connecting them.

(d) Measure the resistance of the wire harness side connector.

Standard resistance:





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

5. CHECK FRONT SEAT WIRE RH (FOR SHORT)

(a) Disconnect the service wire from connector C.





(b) Measure the resistance of the wire harness side connector.

Standard resistance:





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

6. CHECK FRONT SEAT WIRE RH (TO GROUND)

(a) Measure the resistance of the wire harness side connector.





Standard resistance:





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

7. CHECK FOR DTC

(a) Connect the connectors to the occupant classification ECU and the front occupant classification sensor RH.

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

(c) Turn the ignition switch to ON.

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

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 to ON.

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

OK:

DTC B1781 is not output.

HINT
DTCs other than DTC B1781 may be output at this time, but they are not related to this check.

OK -- USE SIMULATION METHOD TO CHECK
NG -- Continue to next step.

8. 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 Components.

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

NEXT -- Continue to next step.

9. PERFORM ZERO POINT CALIBRATION

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

(b) Connect the Techstream to the DLC3.

(c) Turn the ignition switch to ON.

(d) Using the Techstream, perform the zero point calibration Programming and Relearning.

OK:

"Zero Point Calibration is complete." is displayed.

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

10. PERFORM SENSITIVITY CHECK

(a) Using the Techstream, perform the sensitivity check Programming and Relearning.

Standard value:

27 to 33 kg (59.52 to 72.75 lb)

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

11. CHECK FOR DTC

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

(b) Turn the ignition switch to ON.

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

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

(d) Turn the ignition switch off.

(e) Turn the ignition switch to ON.

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

OK:

DTC B1781 is not output.

HINT
DTCs other than DTC B1781 may be output at this time, but they are not related to this check.

OK -- END
NG -- Continue to next step.

12. REPLACE FRONT SEAT 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 RH Components.

NEXT -- Continue to next step.

13. PERFORM ZERO POINT CALIBRATION

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

(b) Connect the Techstream to the DLC3.

(c) Turn the ignition switch to ON.

(d) Using the Techstream, perform the zero point calibration Programming and Relearning.

OK:

"Zero Point Calibration is complete." is displayed.

NEXT -- Continue to next step.

14. PERFORM SENSITIVITY CHECK

(a) Using the Techstream, perform the sensitivity check Programming and Relearning.

Standard value:

27 to 33 kg (59.52 to 72.75 lb)

NEXT -- END