Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Rear Seat Belt Warning Light Malfunction

DESCRIPTION

The main body ECU (multiplex network body ECU) detects whether either the rear doors are open or closed based on the courtesy light switch condition and then sends the rear door status signal to the combination meter assembly. The combination meter assembly detects rear seat belt state. The rear seat belt warning light on the radio and display receiver assembly illuminates, blinks or turns off in accordance with the rear door state, vehicle speed and rear seat belt state.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • The seat belt warning system uses the CAN communication system. First, confirm that there is no malfunction in the CAN communication system. Refer to the How to Proceed with Troubleshooting procedure.

    Click here

  • Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.

READ VALUE USING TECHSTREAM (REAR DOOR COURTESY LIGHT SWITCH)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Main Body / Data List.

(e) Read the Data List according to the display on the Techstream.

Body Electrical > Main Body > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

RR Door Courtesy SW

Rear door courtesy light switch RH

ON or OFF

ON: Rear door RH open

OFF: Rear door RH closed

-

RL Door Courtesy SW

Rear door courtesy light switch LH

ON or OFF

ON: Rear door LH open

OFF: Rear door LH closed

-

Body Electrical > Main Body > Data List

Tester Display

RR Door Courtesy SW

RL Door Courtesy SW

OK:

The Techstream display changes correctly in response to the rear door condition.

NG

GO TO LIGHTING SYSTEM

OK

2.

CHECK REAR SEAT BELT WARNING

(a) Check the rear seat belt warning function.

Click here

*1

Rear Seat Belt Warning Light (Radio and Display Receiver Assembly)

*a

LH

*b

Center

*c

RH

Result

Proceed to

The rear seat belt warning lights operation is normal

A

The rear seat belt warning lights (all seats) do not operate normally

B

The rear seat belt warning light (RH) does not operate normally

C

The rear seat belt warning light (center) does not operate normally

D

The rear seat belt warning light (LH) does not operate normally

E

A

USE SIMULATION METHOD TO CHECK

C

GO TO STEP 6

D

GO TO STEP 10

E

GO TO STEP 14

B

3.

PERFORM ACTIVE TEST USING TECHSTREAM (REAR SEAT BELT WARNING LIGHT)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Combination Meter / Active Test.

(e) Perform the Active Test according to the display on the Techstream.

Body Electrical > Combination Meter > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Rear Seat Belt Warning

Rear seat belt warning light

OFF/ON

-

Body Electrical > Combination Meter > Active Test

Tester Display

Rear Seat Belt Warning

Result

Proceed to

The rear seat belt warning light does not operate normally

A

The rear seat belt warning light operates normally

B

B

REPLACE COMBINATION METER ASSEMBLY

A

4.

CHECK HARNESS AND CONNECTOR (POWER SOURCE - RADIO AND DISPLAY RECEIVER ASSEMBLY)

(a) Disconnect the G20 radio and display receiver assembly connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

G20-2 (IG+) - Body ground

Power switch on (IG)

11 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

5.

CHECK HARNESS AND CONNECTOR (RADIO AND DISPLAY RECEIVER ASSEMBLY - COMBINATION METER ASSEMBLY)

(a) Reconnect the G20 radio and display receiver assembly connector.

(b) Disconnect the G16 combination meter assembly connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

G16-18 (RLMT) - Body ground

Power switch on (IG)

11 to 14 V

G16-19 (RCMT) - Body ground

Power switch on (IG)

11 to 14 V

G16-20 (RRMT) - Body ground

Power switch on (IG)

11 to 14 V

OK

REPLACE COMBINATION METER ASSEMBLY

NG

REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY

6.

READ VALUE USING TECHSTREAM (REAR SEAT BELT BUCKLE SWITCH (FOR RH))

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Combination Meter / Data List.

(e) Read the Data List according to the display on the Techstream.

Body Electrical > Combination Meter > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Rear Right Seat Buckle / Occupant Detection Warning Switch

Rear seat inner with center belt RH buckle signal

ON or OFF

OFF: Rear RH seat belt fastened

ON: Rear RH seat belt not fastened

-

Body Electrical > Combination Meter > Data List

Tester Display

Rear Right Seat Buckle / Occupant Detection Warning Switch

Result

Proceed to

ON or OFF does not appear on the Techstream according to the rear seat belt condition

A

ON or OFF appears on the Techstream according to the rear seat belt condition

B

B

GO TO STEP 8

A

7.

CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - REAR SEAT INNER WITH CENTER BELT ASSEMBLY RH - BODY GROUND)

(a) Disconnect the G16 combination meter assembly connector.

(b) Disconnect the K70 rear seat inner with center belt assembly RH connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

G16-26 (RRSB) - K70-4 (RBR+)

Always

Below 1 Ω

G16-26 (RRSB) or K70-4 (RBR+) - Body ground

Always

10 kΩ or higher

K70-3 (RBR-) - Body ground

Always

Below 1 Ω

OK

REPLACE REAR SEAT INNER WITH CENTER BELT ASSEMBLY RH

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

8.

PERFORM ACTIVE TEST USING TECHSTREAM (REAR SEAT BELT WARNING LIGHT)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Combination Meter / Active Test.

(e) Perform the Active Test according to the display on the Techstream.

Body Electrical > Combination Meter > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Rear Seat Belt Warning

Rear seat belt warning light

OFF/ON

-

Body Electrical > Combination Meter > Active Test

Tester Display

Rear Seat Belt Warning

Result

Proceed to

The rear seat belt warning light does not operate normally

A

The rear seat belt warning light operates normally

B

B

REPLACE COMBINATION METER ASSEMBLY

A

9.

CHECK HARNESS AND CONNECTOR (RADIO AND DISPLAY RECEIVER ASSEMBLY - COMBINATION METER ASSEMBLY)

(a) Disconnect the G16 combination meter assembly connector.

(b) Disconnect the G20 radio and display receiver assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

G16-20 (RRMT) - G20-4 (RRID)

Always

Below 1 Ω

G16-20 (RRMT) or G20-4 (RRID) - Body ground

Always

10 kΩ or higher

OK

REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

10.

READ VALUE USING TECHSTREAM (REAR SEAT BELT BUCKLE SWITCH (FOR CENTER))

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Combination Meter / Data List.

(e) Read the Data List according to the display on the Techstream.

Body Electrical > Combination Meter > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Rear Center Seat Buckle / Occupant Detection Warning Switch

Rear seat inner belt LH (for center) buckle signal

ON or OFF

OFF: Rear LH seat belt (for center) fastened

ON: Rear LH seat belt (for center) not fastened

-

Body Electrical > Combination Meter > Data List

Tester Display

Rear Center Seat Buckle / Occupant Detection Warning Switch

Result

Proceed to

ON or OFF does not appear on the Techstream according to the rear seat belt condition

A

ON or OFF appears on the Techstream according to the rear seat belt condition

B

B

GO TO STEP 12

A

11.

CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - REAR SEAT INNER BELT ASSEMBLY LH - BODY GROUND)

(a) Disconnect the G16 combination meter assembly connector.

(b) Disconnect the K71 rear seat inner belt assembly LH connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

G16-25 (RCSB) - K71-1 (CBR+)

Always

Below 1 Ω

G16-25 (RCSB) or K71-1 (CBR+) - Body ground

Always

10 kΩ or higher

K71-2 (CBR-) - Body ground

Always

Below 1 Ω

OK

REPLACE REAR SEAT INNER BELT ASSEMBLY LH

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

12.

PERFORM ACTIVE TEST USING TECHSTREAM (REAR SEAT BELT WARNING LIGHT)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Combination Meter / Active Test.

(e) Perform the Active Test according to the display on the Techstream.

Body Electrical > Combination Meter > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Rear Seat Belt Warning

Rear seat belt warning light

OFF/ON

-

Body Electrical > Combination Meter > Active Test

Tester Display

Rear Seat Belt Warning

Result

Proceed to

The rear seat belt warning light does not operate normally

A

The rear seat belt warning light operates normally

B

B

REPLACE COMBINATION METER ASSEMBLY

A

13.

CHECK HARNESS AND CONNECTOR (RADIO AND DISPLAY RECEIVER ASSEMBLY - COMBINATION METER ASSEMBLY)

(a) Disconnect the G16 combination meter assembly connector.

(b) Disconnect the G20 radio and display receiver assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

G16-19 (RCMT) - G20-12 (RCID)

Always

Below 1 Ω

G16-19 (RCMT) or G20-12 (RCID) - Body ground

Always

10 kΩ or higher

OK

REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

14.

READ VALUE USING TECHSTREAM (REAR SEAT BELT BUCKLE SWITCH (FOR LH))

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Combination Meter / Data List.

(e) Read the Data List according to the display on the Techstream.

Body Electrical > Combination Meter > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Rear Left Seat Buckle / Occupant Detection Warning Switch

Rear seat inner belt LH (for LH) buckle signal

ON or OFF

OFF: Rear LH seat belt (for LH) fastened

ON: Rear LH seat belt (for LH) not fastened

-

Body Electrical > Combination Meter > Data List

Tester Display

Rear Left Seat Buckle / Occupant Detection Warning Switch

Result

Proceed to

ON or OFF does not appear on the Techstream according to the rear seat belt condition

A

ON or OFF appears on the Techstream according to the rear seat belt condition

B

B

GO TO STEP 16

A

15.

CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - REAR SEAT INNER BELT ASSEMBLY LH - BODY GROUND)

(a) Disconnect the G16 combination meter assembly connector.

(b) Disconnect the K71 rear seat inner belt assembly LH connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

G16-24 (RLSB) - K71-5 (LBR+)

Always

Below 1 Ω

G16-24 (RLSB) or K71-5 (LBR+) - Body ground

Always

10 kΩ or higher

K71-4 (LBR-) - Body ground

Always

Below 1 Ω

OK

REPLACE REAR SEAT INNER BELT ASSEMBLY LH

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

16.

PERFORM ACTIVE TEST USING TECHSTREAM (REAR SEAT BELT WARNING LIGHT)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Combination Meter / Active Test.

(e) Perform the Active Test according to the display on the Techstream.

Body Electrical > Combination Meter > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Rear Seat Belt Warning

Rear seat belt warning light

OFF/ON

-

Body Electrical > Combination Meter > Active Test

Tester Display

Rear Seat Belt Warning

Result

Proceed to

The rear seat belt warning light does not operate normally

A

The rear seat belt warning light operates normally

B

B

REPLACE COMBINATION METER ASSEMBLY

A

17.

CHECK HARNESS AND CONNECTOR (RADIO AND DISPLAY RECEIVER ASSEMBLY - COMBINATION METER ASSEMBLY)

(a) Disconnect the G16 combination meter assembly connector.

(b) Disconnect the G20 radio and display receiver assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

G16-18 (RLMT) - G20-5 (RLID)

Always

Below 1 Ω

G16-18 (RLMT) or G20-5 (RLID) - Body ground

Always

10 kΩ or higher

OK

REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

    Problem Symptoms Table

    System Description

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