Last Modified: 05-13-2024 6.11:8.1.0 Doc ID: RM100000001BW2Y
Model Year Start: 2019 Model: GR Corolla Prod Date Range: [06/2018 - 03/2019]
Title: SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM (for Gasoline Model): B1782; Rear Occupant Classification Sensor LH Circuit Malfunction; 2019 - 2020 MY Corolla Corolla Hatchback GR Corolla [06/2018 - 03/2019]

DTC

B1782

Rear Occupant Classification Sensor LH Circuit Malfunction

DESCRIPTION

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

DTC B1782 is stored when a malfunction is detected in the rear occupant classification sensor LH circuit.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

B1782

Rear Occupant Classification Sensor LH Circuit Malfunction
  • The occupant detection ECU detects a line short, short to ground or B+, or an open in the rear occupant classification sensor LH circuit.
  • Rear occupant classification sensor LH malfunction
  • Occupant detection ECU malfunction
  • Front seat wire RH
  • Rear occupant classification sensor LH (Front seat adjuster assembly RH)*
  • Occupant detection ECU
  • *: The rear occupant classification sensor LH is built into the front seat adjuster assembly RH.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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

Click here 2019 MY Corolla Corolla Hatchback Corolla HV GR Corolla [06/2018 - 01/2019]; INTRODUCTION: REPAIR INSTRUCTION: INITIALIZATION 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; INTRODUCTION: REPAIR INSTRUCTION: INITIALIZATION

HINT:

  • When DTC B1650 is stored as a result of troubleshooting for the airbag system, check the DTCs stored in the occupant detection ECU. When DTC B1782 is output, perform troubleshooting for this DTC first.
  • If it is difficult to perform troubleshooting (wire harness inspection), 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 engine switch off.

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

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

OK:

The connectors are properly connected.

HINT:

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

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

(e) Check that the terminals of the connectors are not deformed or damaged.

OK:

The terminals are not deformed or damaged.

NG

REPLACE FRONT SEAT WIRE RH
OK

2.

CHECK FRONT SEAT WIRE RH

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

*1

Rear Occupant Classification Sensor LH

*2

Occupant Detection ECU

*3

Front Seat Wire RH

*4

Service Wire

*a

Front view of wire harness connector

(to Occupant Detection ECU)

*b

Front view of wire harness connector

(to Rear Occupant Classification Sensor LH)

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

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

j3-2 (SVC3) - Body ground

Engine switch on (IG)

Below 1 V

j3-4 (SIG3) - Body ground

Engine switch on (IG)

Below 1 V

j3-6 (SGD3) - Body ground

Engine switch on (IG)

Below 1 V

(d) Turn the engine switch off.

(e) Disconnect the cable from the negative (-) battery terminal.

(f) Using service wires, connect terminals 1 (SVC) and 3 (SGD), and terminals 2 (SIG) and 3 (SGD) of connector C.

NOTICE:

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

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

j3-2 (SVC3) - j3-6 (SGD3)

Always

Below 1 Ω

j3-4 (SIG3) - j3-6 (SGD3)

Always

Below 1 Ω

(h) Disconnect the service wires from connector C.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

j3-2 (SVC3) - j3-6 (SGD3)

Always

1 MΩ or higher

j3-4 (SIG3) - j3-6 (SGD3)

Always

1 MΩ or higher

j3-2 (SVC3) - j3-4 (SIG3)

Always

1 MΩ or higher

j3-2 (SVC3) - Body ground

Always

1 MΩ or higher

j3-4 (SIG3) - Body ground

Always

1 MΩ or higher

j3-6 (SGD3) - Body ground

Always

1 MΩ or higher
NG

REPLACE FRONT SEAT WIRE RH
OK

3.

CHECK DTC

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

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

(c) Turn the engine switch on (IG), and wait for at least 60 seconds.

(d) Clear the DTCs stored in the occupant detection ECU.

Body Electrical > Occupant Detection > Clear DTCs

(e) Clear the DTCs stored in the airbag sensor assembly.

Body Electrical > SRS Airbag > Clear DTCs

(f) Turn the engine switch off.

(g) Turn the engine switch on (IG), and wait for at least 10 seconds.

(h) Check for DTCs.

Body Electrical > Occupant Detection > Trouble Codes

OK:

DTC B1782 is not output.

HINT:

Codes other than DTC B1782 may be output at this time, but they are not related to this check.

(i) Turn the engine switch off.

OK

USE SIMULATION METHOD TO CHECK

NG

4.

CHECK OCCUPANT DETECTION ECU

(a) Disconnect the cable from the negative (-) battery terminal.

(b) Replace the occupant detection ECU with a known good one.

Click here 2019 MY Corolla Corolla Hatchback Corolla HV GR Corolla [06/2018 - 01/2019]; SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION ECU: REMOVAL 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION ECU: REMOVAL

HINT:

Perform the following inspection using known good parts from another vehicle if possible.

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

(d) Turn the engine switch on (IG), and wait for at least 60 seconds.

(e) Clear the DTCs stored in the occupant detection ECU.

Body Electrical > Occupant Detection > Clear DTCs

(f) Clear the DTCs stored in the airbag sensor assembly.

Body Electrical > SRS Airbag > Clear DTCs

(g) Turn the engine switch off.

(h) Turn the engine switch on (IG), and wait for at least 10 seconds.

(i) Check for DTCs.

Body Electrical > Occupant Detection > Trouble Codes

OK:

DTC B1782 is not output.

HINT:

Codes other than DTC B1782 may be output at this time, but they are not related to this check.

(j) Turn the engine switch off.

(k) Disconnect the cable from the negative (-) battery terminal.

(l) Restore the occupant detection ECU that was installed for testing to its original location.

Click here 2019 MY Corolla Corolla Hatchback Corolla HV GR Corolla [06/2018 - 01/2019]; SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION ECU: REMOVAL 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION ECU: REMOVAL

NG

GO TO STEP 7

OK

5.

REPLACE OCCUPANT DETECTION ECU

(a) Turn the engine switch off.

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

(c) Replace the occupant detection ECU with a new one.

Click here 2019 MY Corolla Corolla Hatchback Corolla HV GR Corolla [06/2018 - 01/2019]; SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION ECU: REMOVAL 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION ECU: REMOVAL

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

NEXT

6.

PERFORM ZERO POINT CALIBRATION

(a) Using the Techstream, perform Zero Point Calibration.

Click here 2019 - 2020 MY Corolla Corolla Hatchback GR Corolla [06/2018 - 03/2019]; SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM (for Gasoline Model): INITIALIZATION

NEXT

END

7.

REPLACE FRONT SEAT ADJUSTER ASSEMBLY RH

(a) Turn the engine switch off.

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

(c) Replace the front seat adjuster assembly RH.

Click here 2019 MY Corolla Corolla Hatchback Corolla HV GR Corolla [06/2018 - 01/2019]; SEAT: FRONT SEAT ASSEMBLY (for Manual Seat): REMOVAL 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; SEAT: FRONT SEAT ASSEMBLY (for Manual Seat): REMOVAL

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

NEXT

8.

PERFORM ZERO POINT CALIBRATION

(a) Using the Techstream, perform Zero Point Calibration.

Click here 2019 - 2020 MY Corolla Corolla Hatchback GR Corolla [06/2018 - 03/2019]; SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM (for Gasoline Model): INITIALIZATION

NEXT

END