SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: B1780; Front Occupant Classification Sensor LH Circuit Malfunction; 2019 - 2024 MY RAV4 RAV4 HV [02/2019

Last Modified: 01-30-2024	6.11:8.1.0	Doc ID: RM100000001HIBE
Model Year Start: 2019	Model: RAV4	Prod Date Range: [02/2019 - ]
Title: SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: B1780; Front Occupant Classification Sensor LH Circuit Malfunction; 2019 - 2024 MY RAV4 RAV4 HV [02/2019 - ]

DTC

B1780

Front Occupant Classification Sensor LH Circuit Malfunction

DESCRIPTION

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

DTC B1780 is stored when a malfunction is detected in the front occupant classification sensor LH circuit.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
B1780	Front Occupant Classification Sensor LH Circuit Malfunction	The occupant detection ECU detects a line short, short to ground or B+, or an open in the front occupant classification sensor LH circuit. Front occupant classification sensor LH malfunction Occupant detection ECU malfunction	Front seat wire RH Front seat adjuster assembly RH (Front occupant classification sensor LH)* Occupant detection ECU

*: The front occupant classification sensor LH is built into the front seat adjuster assembly RH.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

After turning the ignition switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal.
Click here
When disconnecting the cable from the negative (-) auxiliary battery terminal while performing repairs, some systems need to be initialized after the cable is reconnected.
Click here

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 B1780 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 CONNECTION OF CONNECTORS

(a) Turn the ignition switch off.

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

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

Connectors are not properly connected

CONNECT CONNECTORS PROPERLY

Connectors are properly connected

2.	CHECK CONNECTORS

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

(b) Check that the connectors (on the occupant detection ECU side and front occupant classification sensor LH side) are not damaged.

Connectors are deformed or damaged

REPLACE FRONT SEAT WIRE RH

Connectors are not deformed or damaged

3.	CHECK FRONT SEAT WIRE RH

(a) Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.

*1	Front 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 Front Occupant Classification Sensor LH)

(b) Turn the ignition switch to ON.

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
S22-1 - Body ground	Ignition switch ON	Below 1 V
S22-3 - Body ground
S22-5 - Body ground

(d) Turn the ignition switch off.

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

(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 a service wire.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
S22-1 - S22-5	Always	Below 1 Ω
S22-3 - S22-5	Always	Below 1 Ω

(h) Disconnect the service wire from connector C.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
S22-1 - S22-5	Always	1 MΩ or higher
S22-3 - S22-5
S22-1 - S22-3
S22-1 - Body ground
S22-3 - Body ground
S22-5 - Body ground

REPLACE FRONT SEAT WIRE RH

CHECK DTC

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

(b) Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.

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

Click here

Body Electrical > Occupant Detection > Clear DTCs

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

Click here

Body Electrical > SRS Airbag > Clear DTCs

(f) Turn the ignition switch off.

(g) Turn the ignition switch to ON, and wait for at least 60 seconds.

(h) Check the DTCs stored in the occupant detection ECU.

Click here

Body Electrical > Occupant Detection > Trouble Codes

HINT:

Codes other than DTC B1780 may be output at this time, but they are not related to this check.

DTC B1780 is not output

USE SIMULATION METHOD TO CHECK

DTC B1780 is output

5.	CHECK OCCUPANT DETECTION ECU

(a) Turn the ignition switch off.

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

Click here

HINT:

Perform the inspection using parts from a normal vehicle if possible.

CHECK DTC

(a) Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.

(b) Turn the ignition switch to ON, and wait for at least 60 seconds.

Click here

Body Electrical > Occupant Detection > Clear DTCs

(d) Clear the DTCs stored in the airbag ECU assembly.

Click here

Body Electrical > SRS Airbag > Clear DTCs

(e) Turn the ignition switch off.

(f) Turn the ignition switch to ON, and wait for at least 60 seconds.

(g) Check the DTCs stored in the occupant detection ECU.

Click here

Body Electrical > Occupant Detection > Trouble Codes

HINT:

Codes other than DTC B1780 may be output at this time, but they are not related to this check.

(h) Turn the ignition switch off.

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

DTC B1780 is not output

GO TO STEP 9

DTC B1780 is output

7.	REPLACE FRONT SEAT ADJUSTER ASSEMBLY RH

(a) Replace the front seat adjuster assembly RH with a new one.

Click here

(b) Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.

8.	PERFORM ZERO POINT CALIBRATION

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

Click here

Body Electrical > Occupant Detection > Utility

Tester Display
Zero Point Calibration

END (FRONT SEAT ADJUSTER ASSEMBLY RH WAS DEFECTIVE)

9.	PERFORM ZERO POINT CALIBRATION

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

Click here

Body Electrical > Occupant Detection > Utility

Tester Display
Zero Point Calibration

END (OCCUPANT DETECTION ECU WAS DEFECTIVE)