SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: B1771; Passenger Side Buckle Switch Circuit Malfunction; 2019 MY RAV4 RAV4 HV [11/2018

Last Modified: 01-30-2024	6.11:8.1.0	Doc ID: RM100000001G1HJ
Model Year Start: 2019	Model: RAV4	Prod Date Range: [11/2018 - 02/2019]
Title: SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: B1771; Passenger Side Buckle Switch Circuit Malfunction; 2019 MY RAV4 RAV4 HV [11/2018 - 02/2019]

DTC

B1771

Passenger Side Buckle Switch Circuit Malfunction

DESCRIPTION

The passenger side buckle switch circuit consists of the occupant detection ECU and front seat inner belt assembly RH (front passenger side buckle switch).

DTC B1771 is stored when a malfunction is detected in the front passenger side buckle switch circuit.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
B1771	Passenger Side Buckle Switch Circuit Malfunction	The occupant detection ECU detects a line short, short to ground or B+, or an open in the front passenger side buckle switch circuit. Front passenger side buckle switch malfunction Occupant detection ECU malfunction	Front seat wire RH Front seat inner belt assembly RH (Front passenger side buckle switch) Occupant detection ECU

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

After turning the ignition switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal.
Click here
When disconnecting the cable from the negative (-) 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 B1771 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 (-) battery terminal, and wait for at least 90 seconds.

(c) Check that the connectors are properly connected to the occupant detection ECU and front seat inner belt assembly RH.

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 seat inner belt assembly RH.

(b) Check that the connectors (on the occupant detection ECU side and front seat inner belt assembly RH 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 (-) battery terminal, and wait for at least 2 seconds.

*1	Front Seat Inner Belt Assembly RH
*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 Seat Inner Belt Assembly RH)

(b) Turn the ignition switch to ON.

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
S21-7 - Body ground	Ignition switch ON	Below 1 V
S21-9 - Body ground	Ignition switch ON	Below 1 V

(d) Turn the ignition switch off.

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

(f) Using a service wire, connect terminals 1 and 2 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
S21-7 - S21-9	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
S21-7 - S21-9	Always	1 MΩ or higher
S21-7 - Body ground
S21-9 - Body ground

REPLACE FRONT SEAT WIRE RH

CHECK DTC

(a) Connect the connectors to the occupant detection ECU and front seat inner belt assembly RH.

(b) Connect the cable to the negative (-) 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 B1771 may be output at this time, but they are not related to this check.

DTC B1771 is not output

USE SIMULATION METHOD TO CHECK

DTC B1771 is output

5.	REPLACE FRONT SEAT INNER BELT ASSEMBLY RH

(a) Turn the ignition switch off.

(b) Disconnect the cable from the negative (-) 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 (-) 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 B1771 may be output at this time, but they are not related to this check.

DTC B1771 is not output

END (FRONT SEAT INNER BELT ASSEMBLY RH WAS DEFECTIVE)

DTC B1771 is output

7.	REPLACE OCCUPANT DETECTION ECU

(a) Turn the ignition switch off.

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

Click here

(d) Connect the cable to the negative (-) 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 (OCCUPANT DETECTION ECU WAS DEFECTIVE)