DTC B1783 Rear Occupant Classification Sensor RH Circuit Malfunction

DESCRIPTION

The rear occupant classification sensor RH circuit consists of the occupant classification ECU and the rear occupant classification sensor RH.
DTC B1783 is recorded when a malfunction is detected in the rear occupant classification sensor RH circuit.

DTC No.	DTC Detecting Condition	Trouble Area
B1783	Occupant classification ECU detects line short circuit signal, open circuit signal, short circuit to ground signal or short circuit to B+ signal in rear occupant classification sensor RH circuit for 2 seconds Rear occupant classification sensor RH malfunction Occupant classification ECU malfunction	Front seat wire RH Front seat assembly RH (Rear occupant classification sensor RH) Occupant classification ECU

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.

1.CHECK DTC

Turn the ignition switch to the on position.

Clear the DTCs stored in the memory (Click here).
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 (Click here).
OK:
DTC B1783 is not output.
HINT:
Codes other than DTC B1783 may be output at this time, but they are not related to this check.

USE SIMULATION METHOD TO CHECK

NG

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 rear occupant classification sensor RH.
OK:
The connectors are properly connected.

CONNECT CONNECTORS

OK

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

Disconnect the connectors from the occupant classification ECU and the rear occupant classification sensor RH.

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

Turn the ignition switch to the on position.

Measure the voltage.
Standard voltage:
Tester connection
Condition
Specified condition
U1-4 (SGD4) -
Body ground
Ignition switch on
Below 1 V
U1-6 (SVC4) -
Body ground
Ignition switch on
Below 1 V
U1-10 (SIG4) -
Body ground
Ignition switch on
Below 1 V

REPAIR OR REPLACE FRONT SEAT WIRE RH

OK

4.CHECK FRONT SEAT WIRE RH (FOR 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 U5-1 (SVC4) and U5-3 (SGD4), and connect U5-2 (SIG4) and U5-3 (SGD4) of connector C.
NOTICE:
Do not forcibly insert the service wire into the terminals of the connector when connecting.

Measure the resistance.
Standard resistance:
Tester connection
Condition
Specified condition
U1-6 (SVC4) -
U1-4 (SGD4)
Always
Below 1 Ω
U1-10 (SIG4) -
U1-4 (SGD4)
Always
Below 1 Ω

REPAIR OR REPLACE FRONT SEAT WIRE RH

OK

5.CHECK FRONT SEAT WIRE RH (FOR SHORT)

Disconnect the service wire from connector C.

Measure the resistance.
Standard resistance:
Tester connection
Condition
Specified condition
U1-6 (SVC4) -
U1-4 (SGD4)
Always
1 MΩ or higher
U1-10 (SIG4) -
U1-4 (SGD4)
Always
1 MΩ or higher
U1-6 (SVC4) -
U1-10 (SIG4)
Always
1 MΩ or higher

REPAIR OR REPLACE FRONT SEAT WIRE RH

OK

6.CHECK FRONT SEAT WIRE RH (TO GROUND)

Measure the resistance.
Standard resistance:
Tester connection
Condition
Specified condition
U1-4 (SGD4) -
Body ground
Always
1 MΩ or higher
U1-6 (SVC4) -
Body ground
Always
1 MΩ or higher
U1-10 (SIG4) -
Body ground
Always
1 MΩ or higher

REPAIR OR REPLACE FRONT SEAT WIRE RH

OK

7.CHECK DTC

Connect the connectors to the occupant classification ECU and the rear 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 (Click here).
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 (Click here).
OK:
DTC B1783 is not output.
HINT:
Codes other than DTC B1783 may be output at this time, but they are not related to this check.

USE SIMULATION METHOD TO CHECK

NG

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 (Click here).
HINT:
Perform the inspection using parts from a normal vehicle if possible.

NEXT

9.PERFORM ZERO POINT CALIBRATION

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

Connect the Techstream to the DLC3.

Turn the ignition switch to the on position.

Using the Techstream, perform the zero point calibration (Click here).
OK:
COMPLETED is displayed.

Go to step 12

OK

10.PERFORM SENSITIVITY CHECK

Using the Techstream, perform the sensitivity check (Click here).
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).

Go to step 12

OK

11.CHECK DTC

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

Turn the ignition switch to the on position.

Clear the DTCs stored in the memory (Click here).
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 (Click here).
OK:
DTC B1783 is not output.
HINT:
Codes other than DTC B1783 may be output at this time, but they are not related to this check.

END

NG

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 (Click here ).

NEXT

13.PERFORM ZERO POINT CALIBRATION

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

Connect the Techstream to the DLC3.

Turn the ignition switch to the on position.

Using the Techstream, perform the zero point calibration (Click here).
OK:
COMPLETED is displayed.

NEXT

14.PERFORM SENSITIVITY CHECK

Using the Techstream, perform the sensitivity check (Click here).
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).

END

Tester connection	Condition	Specified condition
U1-4 (SGD4) - Body ground	Ignition switch on	Below 1 V
U1-6 (SVC4) - Body ground	Ignition switch on	Below 1 V
U1-10 (SIG4) - Body ground	Ignition switch on	Below 1 V