B1780

SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: B1780: Front Occupant Classification Sensor LH Circuit Malfunction
B1780 - Front Occupant Classification Sensor LH Circuit Malfunction

DESCRIPTION

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

DTC B1780 is stored when a malfunction is detected in the front occupant classification sensor LH circuit.





HINT
When DTC B1650/32 is detected as a result of troubleshooting for the airbag system, check the DTCs stored in the occupant detection ECU. When DTC B1780 is output, perform troubleshooting for the DTC.

WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work Service Precautions.

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

PROCEDURE

1. CHECK CONNECTORS

(a) Turn the power switch off.

(b) Disconnect the cable from the negative (-) auxiliary battery terminal.

(c) Check that the connectors are properly connected to the occupant detection ECU and front occupant classification sensor LH.

OK:

The connectors are properly connected.

HINT
If the connectors are not connected securely, reconnect the connectors and proceed to the next inspection.

(d) Disconnect the connectors from the occupant detection ECU and front occupant classification sensor LH.

(e) 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 -- Continue to next step.

2. CHECK FRONT SEAT WIRE RH (SHORT TO B+)

(a) Connect the cable to the negative (-) auxiliary battery terminal.





(b) Turn the power switch on (IG).

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

Standard Voltage:





Text in Illustration





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

3. CHECK FRONT SEAT WIRE RH (OPEN)

(a) Turn the power switch off.





(b) Disconnect the cable from the negative (-) auxiliary battery terminal.

(c) Using SST, connect terminals 1 (SVC1) and 3 (SGD1), and connect terminals 2 (SIG1) and 3 (SGD1) of connector C.

NOTICE:
Do not forcibly insert SST into the terminals of the connector when connecting.

SST : 09843-18040

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

Standard Resistance:





Text in Illustration





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

4. CHECK FRONT SEAT WIRE RH (SHORT)

(a) Disconnect SST from connector C.





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

Standard Resistance:





Text in Illustration





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

5. CHECK FRONT SEAT WIRE RH (SHORT TO GROUND)

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





Standard Resistance:





Text in Illustration





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

6. CHECK DTC

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

(b) Connect the cable to the negative (-) auxiliary battery terminal.

(c) Turn the power switch on (IG).

(d) Clear the DTCs stored in the occupant detection ECU Reading and Clearing Diagnostic Trouble Codes.

(e) Clear the DTCs stored in the airbag sensor assembly Reading and Clearing Diagnostic Trouble Codes.

(f) Turn the power switch off.

(g) Turn the power switch on (IG).

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

OK:

DTC B1780 is not output.

HINT
Codes other than DTC B1780 may be output at this time, but they are not related to this check.

NG -- REPLACE FRONT SEAT CUSHION SPRING ASSEMBLY

OK -- USE SIMULATION METHOD TO CHECK How To Proceed With Troubleshooting

7. REPLACE FRONT SEAT CUSHION SPRING ASSEMBLY

(a) Turn the power switch off.

(b) Disconnect the cable from the negative (-) auxiliary battery terminal.

(c) Replace the front seat cushion spring assembly Disassembly for Manual seat, Disassembly for Power seat).

NEXT -- Continue to next step.

8. PERFORM ZERO POINT CALIBRATION

(a) Connect the cable to the negative (-) auxiliary battery terminal.

(b) Turn the power switch on (IG).

(c) Using the Techstream, perform Zero Point Calibration Programming and Relearning.

NEXT -- Continue to next step.

9. PERFORM SENSITIVITY CHECK

(a) Using the Techstream, perform Sensitivity Check Programming and Relearning.

NEXT -- END