Toyota Sienna Service Manual: Front Occupant Classification Sensor RH Circuit
Malfunction
DTC 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.
DTC No. |
DTC Detecting Condition |
Trouble Area |
B1781 |
- The occupant classification ECU receives a line
short circuit signal, an open circuit signal, a short
circuit to ground signal or a short circuit to B+ signal
in the front occupant classification sensor RH circuit
for 2 seconds.
- Front occupant classification sensor RH
malfunction
- Occupant classification ECU malfunction
|
- Front seat assembly RH (Front occupant
classification sensor RH)
- Occupant classification ECU
- Front seat wire RH
|
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.
1 CHECK DTC
- Turn the ignition switch to the ON position.
- 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.
- Turn the ignition switch to the LOCK position.
- Turn the ignition switch to the ON position.
- Check the DTCs (35).
OK:
DTC B1781 is not output.
HINT:
Codes other than DTC B1781 may be output at this time,
but they are not related to this check.
USE SIMULATION METHOD TO CHECK
2 CHECK CONNECTION OF CONNECTORS
- Turn the ignition switch to the LOCK position.
- Disconnect the negative (-) terminal cable from the
battery, and wait for at least 90 seconds.
- 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.
CONNECT CONNECTORS, THEN GO
TO
STEP 1
3 CHECK FRONT SEAT WIRE RH (SHORT TO B+)
- Disconnect the connectors from the occupant
classification ECU and the front occupant classification
sensor RH.
- Connect the negative (-) terminal cable to the battery.
- Turn the ignition switch to the ON position.
- Measure the voltage according to the value(s) in the
table below.
Standard voltage
REPAIR OR REPLACE FRONT SEAT
WIRE
RH
4 CHECK FRONT SEAT WIRE RH (OPEN)
- Turn the ignition switch to the LOCK position.
- Disconnect the negative (-) terminal cable from the
battery, and wait for at least 90 seconds.
- Using a service wire, connect O6-1 (SVC2) and O6-3
(SGD2), and connect O6-2 (SIG2) and O6-3 (SGD2) of
connector "C".
NOTICE:
Do not forcibly insert a service wire into the
terminals of the connector when connecting.
- Measure the resistance according to the value(s) in the
table below.
Standard resistance
REPAIR OR REPLACE FRONT SEAT
WIRE
RH
5 CHECK FRONT SEAT WIRE RH (SHORT)
- Disconnect the service wire from connector "C".
- Measure the resistance according to the value(s) in the
table below.
Standard resistance
REPAIR OR REPLACE FRONT SEAT
WIRE
RH
6 CHECK FRONT SEAT WIRE RH (SHORT TO GROUND)
- Measure the resistance according to the value(s) in the
table below.
Standard resistance
REPAIR OR REPLACE FRONT SEAT
WIRE
RH
7 CHECK DTC
- Connect the connectors to the occupant classification
ECU and the front occupant classification sensor RH.
- Connect the negative (-) terminal cable to the battery.
- Turn the ignition switch to the ON position.
- 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.
- Turn the ignition switch to the LOCK position.
- Turn the ignition switch to the ON position.
- Check the DTCs (35).
OK:
DTC B1781 is not output.
HINT:
Codes other than DTC B1781 may be output at this time,
but they are not related to this check.
USE SIMULATION METHOD TO CHECK
8 REPLACE OCCUPANT CLASSIFICATION ECU
- Turn the ignition switch to the LOCK position.
- Disconnect the negative (-) terminal cable from the
battery, and wait for at least 90 seconds.
- Replace the occupant classification ECU.
HINT:
Perform the inspection using parts from a normal vehicle
if possible
9 PERFORM ZERO POINT CALIBRATION
- Connect the negative (-) terminal cable to the battery.
- Connect the intelligent tester to the DLC3.
- Turn the ignition switch to the ON position.
- Using the intelligent tester, perform "Zero point
calibration" (28).
OK:
"COMPLETED" is displayed
Go to step 12
10 PERFORM SENSITIVITY CHECK
- Using the intelligent tester, perform "Sensitivity check"
(28).
Standard value:
27 to 33 kg (59.52 to 72.75 lb)
Go to step 12
11 CHECK DTC
- Turn the ignition switch to the ON position.
- 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.
- Turn the ignition switch to the LOCK position.
- Turn the ignition switch to the ON position.
- Check the DTCs (35).
OK:
DTC B1781 is not output.
HINT:
Codes other than DTC B1781 may be output at this time,
but they are not related to this check
END
12 REPLACE FRONT SEAT ASSEMBLY RH
- Turn the ignition switch to the LOCK position.
- Disconnect the negative (-) terminal cable from the
battery, and wait for at least 90 seconds.
- Replace the front seat assembly RH (
for flat type, SE-48 for manual seat, SE-58 for power
seat).
13 PERFORM ZERO POINT CALIBRATION
- Connect the negative (-) terminal cable to the battery.
- Connect the intelligent tester to the DLC3.
- Turn the ignition switch to the ON position.
- Using the intelligent tester, perform "Zero point
calibration" (28).
OK:
"COMPLETED" is displayed.
14 PERFORM SENSITIVITY CHECK
- Using the intelligent tester, perform "Sensitivity check"
(28).
Standard value:
27 to 33 kg (59.52 to 72.75 lb)
END
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