Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Seat Heater for Front Left Seat does not Operate

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Vehicle Interior / Seat / Seat Heater System(for Hv Model) / Seat Heater for Front Left Seat does not Operate

DESCRIPTION

When the seat heater switch of the seat heater switch (radio and display receiver assembly) is operated, the air conditioning amplifier assembly receives a signal and operates the front seat heater.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • If the auxiliary battery voltage becomes low, auxiliary battery load control will operate in order to ensure sufficient power is supplied to the power steering system. In this case, the seat heater system (for HV model) may not operate.
  • Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.

CLEAR DTC

(a) Clear the DTCs.

Click here

Body Electrical > Air Conditioner > Clear DTCs
NEXT

2.

CHECK FOR DTC

(a) Check for DTCs.

Click here

Body Electrical > Air Conditioner > Trouble Codes

OK:

DTC B14B5 and B14C1 are not output.

NG

GO TO DIAGNOSTIC TROUBLE CODE CHART

OK

3.

PERFORM ACTIVE TEST USING TECHSTREAM

(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 / Air Conditioner / Active Test.

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

Body Electrical > Air Conditioner > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Front Left Seat Heater

Front seat LH side seat heater operation

OFF or ON

-
Body Electrical > Air Conditioner > Active Test

Tester Display

Front Left Seat Heater

OK:

The seat heater operates normally.

OK

REPLACE SEAT HEATER SWITCH (RADIO AND DISPLAY RECEIVER ASSEMBLY)

NG

4.

INSPECT FRONT SEATBACK HEATER ASSEMBLY LH

(a) Remove the front seatback heater assembly LH.

Click here

(b) Inspect the front seatback heater assembly LH.

Click here

NG

REPLACE FRONT SEATBACK HEATER ASSEMBLY LH

OK

5.

CHECK HARNESS AND CONNECTOR (IG POWER SUPPLY - FRONT SEAT CUSHION HEATER ASSEMBLY LH - BODY GROUND)

(a) Disconnect the R26 front seat cushion heater assembly LH connector.

*a

Front view of wire harness connector

(to Front Seat Cushion Heater Assembly LH)

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

R26-1 (B) - Body ground

Power switch on (IG)

11 to 14 V

R26-1 (B) - Body ground

Power switch off

Below 1 V

Standard Resistance:

Tester Connection

Condition

Specified Condition

R26-2 (E) - Body ground

Always

Below 1 Ω
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

6.

CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - FRONT SEAT CUSHION HEATER ASSEMBLY LH)

(a) Reconnect the R26 front seat cushion heater assembly LH connector.

*a

Front view of wire harness connector

(to Air Conditioning Amplifier Assembly)

(b) Disconnect the G37 air conditioning amplifier assembly connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

G37-15 (SHD+) - Body ground

Power switch on (IG)

5 to 13 V
NG

GO TO STEP 8

OK

7.

CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY

(a) Reconnect the G37 air conditioning amplifier assembly connector.

(b) Remove the air conditioning amplifier assembly with its connectors still connected.

Click here

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

*a

Component with harness connected

(Air Conditioning Amplifier Assembly)

-

-

Standard Voltage:

Tester Connection

Condition

Specified Condition

G37-15 (SHD+) - G35-4 (GND)

Power switch on (IG), seat heater switch (radio and display receiver assembly) on (LO)

Below 1 V
OK

REPLACE FRONT SEAT CUSHION HEATER ASSEMBLY LH

NG

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

8.

CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - FRONT SEAT CUSHION HEATER ASSEMBLY LH)

(a) Disconnect the R26 front seat cushion heater assembly LH connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

G37-15 (SHD+) - R26-6 (SWL)

Always

Below 1 Ω
OK

REPLACE FRONT SEAT CUSHION HEATER ASSEMBLY LH

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
    Problem Symptoms Table

    Seat Heater for Front Right Seat does not Operate

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    Toyota Avalon (XX50) 2019-2022 Owners Manual

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