Toyota Avalon (XX50): Climate Control Seat System(for Gasoline Model)

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Vehicle Interior / Seat / Climate Control Seat System(for Gasoline Model)

Climate Control Seat System does not Operate

DESCRIPTION

When the engine switch is on and the climate control switch is operated, the air conditioning amplifier assembly receives climate control switch position signals and then sends airflow amount signals to each seat cushion climate control blower.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following procedure.
If the battery voltage becomes low, battery load control will operate in order to ensure sufficient power is supplied to the power steering system. In this case, the climate control seat system (for gasoline model) may not operate.
The climate control seat system uses the LIN communication system. Inspect the communication function by following How to Proceed with Troubleshooting. Troubleshoot the climate control seat system after confirming that the communication system is functioning properly.
Click here

PROCEDURE

1.	CHECK DTC OUTPUT

(a) Clear DTCs.

Body Electrical > Air Conditioner > Clear DTCs

(b) Check for DTCs.

Body Electrical > Air Conditioner > Trouble Codes

Result	Proceed to
DTC B14B5 is not output	A
DTC B14B5 output	B

GO TO SEAT HEATER SYSTEM

2.	CHECK CLIMATE CONTROL SEAT OPERATION

(a) Check the climate control seat operation.

Click here

Result	Proceed to
Climate control seat does not operate (for LH)	A
Climate control seat does not operate (for RH)	B
Both climate control seats do not operate	C

GO TO STEP 12

GO TO STEP 21

3.	PERFORM ACTIVE TEST USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

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

(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 Blower	Front LH seat blower operation	OFF or ON	-

Body Electrical > Air Conditioner > Active Test

Tester Display
Front Left Seat Blower

OK:

The seat blower operates normally.

Result	Proceed to
Only seatback climate control blower LH does not operate	A
Only seat cushion climate control blower LH does not operate	B
Both seat blowers do not operate	C

REPLACE SEAT CUSHION CLIMATE CONTROL BLOWER LH

GO TO STEP 7

4.	CHECK HARNESS AND CONNECTOR (SEAT CUSHION CLIMATE CONTROL BLOWER LH - SEATBACK CLIMATE CONTROL BLOWER LH)

(a) Disconnect the a11 seatback climate control blower LH connector.

(b) Disconnect the R34 seat cushion climate control blower LH connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
a11-1 (CTB) - R34-5 (CTB)	Always	Below 1 Ω
a11-1 (CTB) or R34-5 (CTB) - Body ground	Always	10 kΩ or higher
a11-3 (BBS) - R34-6 (BBS)	Always	Below 1 Ω
a11-3 (BBS) or R34-6 (BBS) - Body ground	Always	10 kΩ or higher
a11-4 (BFB-) - R34-4 (BFB-)	Always	Below 1 Ω
a11-4 (BFB-) or R34-4 (BFB-) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

5.	REPLACE SEATBACK CLIMATE CONTROL BLOWER LH

(a) Temporarily replace the seatback climate control blower LH with a new or known good one.

Click here

6.	CHECK CLIMATE CONTROL SEAT OPERATION

(a) Check the climate control seat operation.

Click here

OK:

The climate control seat operates normally.

END (SEATBACK CLIMATE CONTROL BLOWER LH WAS DEFECTIVE)

REPLACE SEAT CUSHION CLIMATE CONTROL BLOWER LH

7.	CHECK HARNESS AND CONNECTOR (IG POWER SUPPLY - SEAT CUSHION CLIMATE CONTROL BLOWER LH - BODY GROUND)

(a) Disconnect the R34 seat cushion climate control blower LH connector.

*a	Front view of wire harness connector (to Seat Cushion Climate Control Blower LH)

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
R34-1 (IG) - Body ground	Engine switch on (IG)	11 to 14 V
R34-1 (IG) - Body ground	Engine switch off	Below 1 V

Standard Resistance:

Tester Connection	Condition	Specified Condition
R34-8 (GND) - Body ground	Always	Below 1 Ω

REPAIR OR REPLACE HARNESS OR CONNECTOR

8.	CHECK HARNESS AND CONNECTOR (SEAT CUSHION CLIMATE CONTROL BLOWER LH - AIR CONDITIONING AMPLIFIER ASSEMBLY)

(a) Disconnect the G35 air conditioning amplifier assembly connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
R34-7 (SIGN) - G35-24 (LOUT)	Always	Below 1 Ω
R34-7 (SIGN) or G35-24 (LOUT) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

9.	CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY

(a) Reconnect the G35 air conditioning amplifier assembly connector.

(b) Reconnect the R34 seat cushion climate control blower LH connector.

*a	Component with harness connected (Air Conditioning Amplifier Assembly)

Measurement Condition

Item	Content
Tester Connection	G35-24 (LOUT) - Body ground
Tool Setting	1 V/DIV., 0.5 ms/DIV.
Vehicle Condition	Engine switch on (IG) Climate control switch on (blower position)

OK:

Waveform is similar to that shown in the illustration.

REPLACE SEAT CUSHION CLIMATE CONTROL BLOWER LH

10.	REPLACE CLIMATE CONTROL SWITCH (RADIO AND DISPLAY RECEIVER ASSEMBLY)

(a) Temporarily replace the climate control switch (radio and display receiver assembly) with a new or known good one.

Click here

11.	CHECK CLIMATE CONTROL SEAT OPERATION

(a) Check the climate control seat operation.

Click here

OK:

The climate control seat operates normally.

END (CLIMATE CONTROL SWITCH (RADIO AND DISPLAY RECEIVER ASSEMBLY) WAS DEFECTIVE)

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

12.	PERFORM ACTIVE TEST USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

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

(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 Right Seat Blower	Front RH seat blower operation	OFF or ON	-

Body Electrical > Air Conditioner > Active Test

Tester Display
Front Right Seat Blower

OK:

The seat blower operates normally.

Result	Proceed to
Only seatback climate control blower RH does not operate	A
Only seat cushion climate control blower RH does not operate	B
Both seat blowers do not operate	C

REPLACE SEAT CUSHION CLIMATE CONTROL BLOWER RH

GO TO STEP 16

13.	CHECK HARNESS AND CONNECTOR (SEAT CUSHION CLIMATE CONTROL BLOWER RH - SEATBACK CLIMATE CONTROL BLOWER RH)

(a) Disconnect the a5 seatback climate control blower RH connector.

(b) Disconnect the R15 seat cushion climate control blower RH connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
R15-5 (CTB) - a5-1 (CTB)	Always	Below 1 Ω
R15-5 (CTB) or a5-1 (CTB) - Body ground	Always	10 kΩ or higher
R15-6 (BBS) - a5-3 (BBS)	Always	Below 1 Ω
R15-6 (BBS) or a5-3 (BBS) - Body ground	Always	10 kΩ or higher
a5-4 (BFB-) - R15-4 (BFB-)	Always	Below 1 Ω
a5-4 (BFB-) or R15-4 (BFB-) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

14.	REPLACE SEATBACK CLIMATE CONTROL BLOWER RH

(a) Temporarily replace the seatback climate control blower RH with a new or known good one.

Click here

15.	CHECK CLIMATE CONTROL SEAT OPERATION

(a) Check the climate control seat operation.

Click here

OK:

The climate control seat operates normally.

END (SEATBACK CLIMATE CONTROL BLOWER RH WAS DEFECTIVE)

REPLACE SEAT CUSHION CLIMATE CONTROL BLOWER RH

16.	CHECK HARNESS AND CONNECTOR (IG POWER SUPPLY - SEAT CUSHION CLIMATE CONTROL BLOWER RH - BODY GROUND)

(a) Disconnect the R15 seat cushion climate control blower RH connector.

*a	Front view of wire harness connector (to Seat Cushion Climate Control Blower RH)

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
R15-1 (IG) - Body ground	Engine switch on (IG)	11 to 14 V
R15-1 (IG) - Body ground	Engine switch off	Below 1 V

Standard Resistance:

Tester Connection	Condition	Specified Condition
R15-8 (GND) - Body ground	Always	Below 1 Ω

REPAIR OR REPLACE HARNESS OR CONNECTOR

17.	CHECK HARNESS AND CONNECTOR (SEAT CUSHION CLIMATE CONTROL BLOWER RH - AIR CONDITIONING AMPLIFIER ASSEMBLY)

(a) Disconnect the G35 air conditioning amplifier assembly connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
R15-7 (SIGN) - G35-23 (ROUT)	Always	Below 1 Ω
R15-7 (SIGN) or G35-23 (ROUT) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

18.	CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY

(a) Reconnect the G35 air conditioning amplifier assembly connector.

(b) Reconnect the R15 seat cushion climate control blower RH connector.

*a	Component with harness connected (Air Conditioning Amplifier Assembly)

Measurement Condition

Item	Content
Tester Connection	G35-23 (ROUT) - Body ground
Tool Setting	1 V/DIV., 0.5 ms/DIV.
Vehicle Condition	Engine switch on (IG) Climate control switch on (blower position)

OK:

Waveform is similar to that shown in the illustration.

REPLACE SEAT CUSHION CLIMATE CONTROL BLOWER RH

19.	REPLACE CLIMATE CONTROL SWITCH (RADIO AND DISPLAY RECEIVER ASSEMBLY)

(a) Temporarily replace the climate control switch (radio and display receiver assembly) with a new or known good one.

Click here

20.	CHECK CLIMATE CONTROL SEAT OPERATION

(a) Check the climate control seat operation.

Click here

OK:

The climate control seat operates normally.

END (CLIMATE CONTROL SWITCH (RADIO AND DISPLAY RECEIVER ASSEMBLY) WAS DEFECTIVE)

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

21.	CHECK HARNESS AND CONNECTOR (IG POWER SUPPLY - CLIMATE CONTROL SWITCH (RADIO AND DISPLAY RECEIVER ASSEMBLY) - BODY GROUND)

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

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
G20-2 (IG+) - Body ground	Engine switch on (IG)	11 to 14 V
G20-2 (IG+) - Body ground	Engine switch off	Below 1 V

Standard Resistance:

Tester Connection	Condition	Specified Condition
G20-6 (GND) - Body ground	Always	Below 1 Ω

REPAIR OR REPLACE HARNESS OR CONNECTOR

22.	REPLACE CLIMATE CONTROL SWITCH (RADIO AND DISPLAY RECEIVER ASSEMBLY)

(a) Temporarily replace the climate control switch (radio and display receiver assembly) with a new or known good one.

Click here

23.	CHECK CLIMATE CONTROL SEAT OPERATION

(a) Check the climate control seat operation.

Click here

OK:

The climate control seat operates normally.

END (CLIMATE CONTROL SWITCH (RADIO AND DISPLAY RECEIVER ASSEMBLY) WAS DEFECTIVE)

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

Data List / Active Test

DATA LIST / ACTIVE TEST

HINT:

Using the Techstream to perform Active Tests allows relays, VSVs, actuators and other items to be operated without removing any parts. This non-intrusive functional inspection can be very useful because intermittent operation may be discovered before parts or wiring is disturbed. Performing Active Tests early in troubleshooting is one way to save diagnostic time. Data List information can be displayed while performing Active Tests.

ACTIVE TEST

(a) Connect the Techstream to the DLC3.

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

(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 Right Seat Blower	Front RH seat blower operation	OFF or ON	-
Front Left Seat Blower	Front LH seat blower operation	OFF or ON	-

Diagnosis System

DIAGNOSIS SYSTEM

CHECK DLC3

(a) Check the DLC3.

Click here

INSPECT BATTERY VOLTAGE

(a) Check the battery voltage.

Standard Voltage:

11 to 14 V

If the voltage is below 11 V, recharge or replace the battery.

How To Proceed With Troubleshooting

CAUTION / NOTICE / HINT

HINT:

Use this procedure to troubleshoot the climate control seat system.
*: Use the Techstream.

PROCEDURE

1.	VEHICLE BROUGHT TO WORKSHOP

2.	CUSTOMER PROBLEM ANALYSIS

(a) Interview the customer to confirm the problem.

Click here

PRE-CHECK

(a) Measure the battery voltage.

Standard Voltage:

11 to 14 V

If the voltage is below 11 V, recharge or replace the battery before proceeding to the next step.

(b) Check the fuses and relays.

(c) Check the connector connections and terminals to make sure that there are no abnormalities such as loose connections, deformation, etc.

4.	CHECK COMMUNICATION FUNCTION OF LIN COMMUNICATION SYSTEM*

(a) Using the Techstream, check for LIN communication system DTCs.

Click here

Result	Proceed to
DTC B14B5 is not output	A
DTC B14B5 is output	B

GO TO SEAT HEATER SYSTEM

5.	PROBLEM SYMPTOMS TABLE

(a) Refer to Problem Symptoms Table.

Click here

Result	Proceed to
Fault is not listed in Problem Symptoms Table	A
Fault is listed in Problem Symptoms Table	B

GO TO STEP 7

6.	OVERALL ANALYSIS AND TROUBLESHOOTING

(a) Terminals of ECU

Click here

(b) On-vehicle Inspection

Click here

7.	REPAIR OR REPLACE

8.	CONFIRMATION TEST

END

On-vehicle Inspection

ON-VEHICLE INSPECTION

PROCEDURE

1. CHECK AIR DUCT

(a) Check that the air ducts of the seat cushion climate control blower and seatback climate control blower are not cracked or damaged and are installed correctly.

2. CHECK CLIMATE CONTROL SEAT SYSTEM

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

(b) Check that each seat cushion climate control blower and seatback climate control blower operates when the climate control switch (radio and display receiver assembly) is turned on.

(c) Check that the seat blower volume changes according to the operation of the climate control switch (radio and display receiver assembly) as follows: HI → MID → LO.

Parts Location

PARTS LOCATION

ILLUSTRATION

CLIMATE CONTROL SWITCH (RADIO AND DISPLAY RECEIVER ASSEMBLY)

AIR CONDITIONING AMPLIFIER ASSEMBLY

NO. 4 RELAY BLOCK ASSEMBLY

- S/HTR F/L FUSE

- S/HTR F/R FUSE

INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

- ECU-IG1 NO. 4 FUSE

DLC3

ILLUSTRATION

*1	SEAT CUSHION CLIMATE CONTROL BLOWER RH	*2	SEATBACK CLIMATE CONTROL BLOWER RH
*3	SEAT CUSHION CLIMATE CONTROL BLOWER LH	*4	SEATBACK CLIMATE CONTROL BLOWER LH

Precaution

PRECAUTION

PRECAUTION FOR DISCONNECTING CABLE FROM NEGATIVE BATTERY TERMINAL

NOTICE:

When disconnecting the cable from the negative (-) battery terminal, initialize the following systems after the cable is reconnected.

System Name	See Procedure
Lane Departure Alert System (w/ Steering Control)
Intelligent Clearance Sonar System
Parking Assist Monitor System
Panoramic View Monitor System
Pre-collision System
Lighting System (for Gasoline Model with Cornering Light)

Problem Symptoms Table

PROBLEM SYMPTOMS TABLE

NOTICE:

If the battery voltage becomes low, battery load control will operate in order to ensure sufficient power is supplied to the power steering system. In this case, the climate control seat system (for gasoline model) may not operate.

HINT:

Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of probability in the "Suspected Area" column of the table. Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.
Inspect the fuses and relays related to this system before inspecting the suspected areas below.

Climate Control Seat System

Symptom	Suspected Area	Link
Seat blower volume is low (front LH seat)	Check that the air ducts are not disconnected or damaged
	Seat cushion climate control blower LH	-
	Seatback climate control blower LH	-
Seat blower volume is low (front RH seat)	Check that the air ducts are not disconnected or damaged
	Seat cushion climate control blower RH	-
	Seatback climate control blower RH	-
Seat blower volume does not change (front LH seat)	Climate control switch (Radio and display receiver assembly)	-
	Seat cushion climate control blower LH	-
	Seatback climate control blower LH	-
	Air conditioning amplifier assembly	-
Seat blower volume does not change (front RH seat)	Climate control switch (Radio and display receiver assembly)	-
	Seat cushion climate control blower RH	-
	Seatback climate control blower RH	-
	Air conditioning amplifier assembly	-
Climate control seat system does not operate	Refer to the "Climate Control Seat System does not Operate".

System Description

SYSTEM DESCRIPTION

GENERAL

(a) The seat blower has 3 levels of volume, controlled by operating the climate control switch (radio and display receiver assembly).

(b) The climate control switch (radio and display receiver assembly) indicator lights indicate the seat blower operating status.

System Diagram

SYSTEM DIAGRAM

Terminals Of Ecu

TERMINALS OF ECU

CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY

(a) Disconnect the G35 air conditioning amplifier assembly connector.

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

HINT:

Measure the values on the wire harness side with the connector disconnected.

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
G35-2 (IG+) - Body ground	LA-GR - Body ground	Air conditioning amplifier power supply	Engine switch off	Below 1 V
G35-2 (IG+) - Body ground	LA-GR - Body ground	Air conditioning amplifier power supply	Engine switch on (IG)	11 to 14 V
G35-4 (GND) - Body ground	W-B - Body ground	Air conditioning amplifier ground	Always	Below 1 Ω

(d) Check for pulses according to the value(s) in the table below.

Terminal No. (Symbol)

Wiring Color

Terminal Description

Condition

Specified Condition

G35-24 (LOUT) - Body ground

G - Body ground

Climate control blower control signal

Engine switch on (IG)
Climate control switch (radio and display receiver assembly) (for LH) on
(blower position)

Pulse generation

(See waveform)

G35-23 (ROUT) - Body ground

LG - Body ground

Climate control blower control signal

Engine switch on (IG)
Climate control switch (radio and display receiver assembly) (for RH) on
(blower position)

Pulse generation

(See waveform)

G35-14 (LIN1) - Body ground

LG - Body ground

Climate control switch signal

Engine switch on (IG)

Pulse generation

(1) Waveform (Reference):

Measurement Condition

Item	Content
Tester Connection	G35-24 (LOUT) - Body ground G35-23 (ROUT) - Body ground
Tool Setting	1 V/DIV., 0.5 ms/DIV.
Vehicle Condition	Engine switch on (IG) Climate control switch (radio and display receiver assembly) on (blower position)

CLIMATE CONTROL SWITCH (RADIO AND DISPLAY RECEIVER ASSEMBLY)

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

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

HINT:

Measure the values on the wire harness side with the connector disconnected.

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
G20-2 (IG+) - Body ground	GR - Body ground	Climate control switch power supply	Engine switch off	Below 1 V
G20-2 (IG+) - Body ground	GR - Body ground	Climate control switch power supply	Engine switch on (IG)	11 to 14 V
G20-6 (GND) - Body ground	W-B - Body ground	Climate control switch ground	Always	Below 1 Ω

(d) Check for pulses according to the value(s) in the table below.

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
G20-8 (LIN1) - Body ground	LG - Body ground	Climate control switch signal	Engine switch on (IG)	Pulse generation

Tongue Plate Stopper

Climate Control Seat System(for Hv Model)

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