B1780

SUPPLEMENTAL RESTRAINT SYSTEM: 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 classification ECU and the front occupant classification sensor LH.

DTC B1780 is recorded when a malfunction is detected in the front occupant classification sensor LH 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 under surface 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 DTC

(a) Turn the ignition switch to the on position.

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

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

(c) Turn the ignition switch to the lock position.

(d) Turn the ignition switch to the on position.

(e) Check the 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.

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

2. CHECK CONNECTION OF CONNECTORS

(a) Turn the ignition switch to the lock position.

(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 occupant classification sensor LH.

OK:

The connectors are properly connected.

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

3. CHECK NO.1 SEAT WIRE (TO B+)

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





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

(c) Turn the ignition switch to the on position.

(d) Measure the voltage.

Standard voltage:





NG -- REPAIR OR REPLACE NO.1 SEAT WIRE
OK -- Continue to next step.

4. CHECK NO.1 SEAT WIRE (FOR OPEN)

(a) Turn the ignition switch to the lock position.





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

(c) Using a service wire, connect Q1-1 (SVC1) and Q1-3 (SGD1), and connect Q1-2 (SIG1) and Q1-3 (SGD1) of connector C.

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

(d) Measure the resistance.

Standard resistance:





NG -- REPAIR OR REPLACE NO.1 SEAT WIRE
OK -- Continue to next step.

5. CHECK NO.1 SEAT WIRE (FOR SHORT)

(a) Disconnect the service wire from connector C.





(b) Measure the resistance.

Standard resistance:





NG -- REPAIR OR REPLACE NO.1 SEAT WIRE
OK -- Continue to next step.

6. CHECK NO.1 SEAT WIRE (TO GROUND)

(a) Measure the resistance.





Standard resistance:





NG -- REPAIR OR REPLACE NO.1 SEAT WIRE
OK -- Continue to next step.

7. CHECK DTC

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

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

(c) Turn the ignition switch to the on position.

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

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

(e) Turn the ignition switch to the lock position.

(f) Turn the ignition switch to the on position.

(g) Check the 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.

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

8. REPLACE OCCUPANT CLASSIFICATION ECU

(a) Turn the ignition switch to the lock position.

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

(c) Replace the occupant classification ECU Removal.

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 negative (-) terminal cable to the battery.

(b) Connect a Techstream to the DLC3.

(c) Turn the ignition switch to the on position.

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

OK:

COMPLETED is displayed.

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

10. PERFORM SENSITIVITY CHECK

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

(1) Confirm that nothing is placed on the passenger seat.

(2) Confirm that the beginning sensor reading is within the standard range.

Standard range:

-3.2 to 3.2 kg (-7 to 7 lb)

(3) Place a 30 kg (66.14 lb) weight (e.g. a lead mass) onto the front passenger seat.

(4) Confirm that the sensitivity is within the standard range.

Standard range:

27 to 33 kg (59.52 to 72.75 lb)

HINT
When performing the sensitivity check, use a solid metal weight (the check result may not be accurate if a liquid weight is used).

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

11. CHECK DTC

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

(b) Turn the ignition switch to the on position.

(c) Clear the DTCs stored in the memory 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 to the lock position.

(e) Turn the ignition switch to the on position.

(f) Check the 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.

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

12. REPLACE FRONT SEAT ASSEMBLY RH

(a) Turn the ignition switch to the lock position.

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

(c) Replace the front seat assembly RH Removal.

NEXT -- Continue to next step.

13. PERFORM ZERO POINT CALIBRATION

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

(b) Connect a Techstream to the DLC3.

(c) Turn the ignition switch to the on position.

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

OK:

COMPLETED is displayed.

NEXT -- Continue to next step.

14. PERFORM SENSITIVITY CHECK

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

(1) Confirm that nothing is placed on the passenger seat.

(2) Confirm that the beginning sensor reading is within the standard range.

Standard range:

-3.2 to 3.2 kg (-7 to 7 lb)

(3) Place a 30 kg (66.14 lb) weight (e.g. a lead mass) onto the front passenger seat.

(4) Confirm that the sensitivity is within the standard range.

Standard range:

27 to 33 kg (59.52 to 72.75 lb)

HINT
When performing the sensitivity check, use a solid metal weight (the check result may not be accurate if a liquid weight is used).

NEXT -- END