B1780

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

DTC 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 fall down. Holding the seat for a long period of time may cause a problem, such as seat rail deformation. Hold the seat only as necessary.

PROCEDURE

1. CHECK DTC
(a) Turn the ignition switch to the ON position.
(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 assembly.
(c) Turn the ignition switch to the LOCK position.
(d) Turn the ignition switch to the ON position.
(e) Check the DTCs .
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
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 CONNECTOR, THEN GO TO STEP 1
OK -- Continue to next step.
3. CHECK FRONT SEAT WIRE RH (SHORT 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 according to the value(s) in the table below.
Standard voltage:






NG -- REPAIR OR REPLACE FRONT SEAT WIRE RH
OK -- Continue to next step.
4. CHECK FRONT SEAT WIRE RH (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 O5-1 (SVC1) and O5-3 (SGD1), and connect O5-2 (SIG1) and O5-3 (SGD1) of connector "C".
NOTE: Do not forcibly insert a service wire into the terminals of the connector when connecting.
(d) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPAIR OR REPLACE FRONT SEAT WIRE RH
OK -- Continue to next step.
5. CHECK FRONT SEAT WIRE RH (SHORT)





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






NG -- REPAIR OR REPLACE FRONT SEAT WIRE RH
OK -- Continue to next step.
6. CHECK FRONT SEAT WIRE RH (SHORT TO GROUND)





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






NG -- REPAIR OR REPLACE FRONT SEAT WIRE RH
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 .
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 .
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
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 .
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 the Techstream to the DLC3.
(c) Turn the ignition switch to the ON position.
(d) Using the Techstream, perform "Zero point calibration" .
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 "Sensitivity check" .
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 DTC
(a) Turn the ignition switch to the ON position.
(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 assembly.
(c) Turn the ignition switch to the LOCK position.
(d) Turn the ignition switch to the ON position.
(e) Check the DTCs .
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 for flat type, for manual seat, for power seat).
NEXT -- Continue to next step.
13. PERFORM ZERO POINT CALIBRATION
(a) Connect the negative (-) terminal cable to the battery.
(b) Connect the Techstream to the DLC3.
(c) Turn the ignition switch to the ON position.
(d) Using the Techstream, perform "Zero point calibration" .
OK:
"Zero Point Calibration is complete." is displayed.
NEXT -- Continue to next step.
14. PERFORM SENSITIVITY CHECK
(a) Using the Techstream, perform "Sensitivity check" .
Standard value:
27 to 33 kg (59.52 to 72.75 lb)
NEXT -- END