The A/C amplifier assembly receives seat position signals when the engine switch is on (IG), and then transmits airflow amount signals to each seat climate blower.

WIRING DIAGRAM

Climate Control Seat System - Climate Control Seat System Does Not Operate. SEAT. Lexus IS250 IS220d GSE20 ALE20

INSPECTION PROCEDURE

1.SYSTEM CHECK

Climate control seat does not operate (Front LH)	A
Climate control seat does not operate (Front RH)	B
Both climate control seats do not operate	C

Go to step 8

Go to step 14

A

2.CHECK WIRE HARNESS

Climate Control Seat System - Climate Control Seat System Does Not Operate. SEAT. Lexus IS250 IS220d GSE20 ALE20

Disconnect the U12 connector.

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

Resistance:
Tester Connection Condition Specified Condition
U12-4 (GND) - Body ground Always Below 1 Ω

Voltage:
Tester Connection Condition Specified Condition
U12-1 (IG) - Body ground Engine switch on (IG) 10 to 14 V

Reconnect the U12 connector.

Disconnect the U13 connector.

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

Resistance:
Tester Connection Condition Specified Condition
U13-1 (GND) - Body ground Always Below 1 Ω

Voltage:
Tester Connection Condition Specified Condition
U13-2 (IG) - Body ground Engine switch on (IG) 10 to 14 V

REPAIR OR REPLACE WIRE HARNESS

OK

3.INSPECT SEAT CLIMATE CONTROL BLOWER

Check the input signal waveform.

Connect the oscilloscope to terminal 3 and body ground with the climate control blower connector still connected.

Check the signal waveform according to the condition(s) in the table below.

Item	Condition
Tool setting	2 V/DIV., 500 μsec/DIV.,
Vehicle condition	Engine switch on (IG), seat heater switch ON

OK:
The waveform is displayed as shown in the illustration.

Result:
NG A
OK (Seat cushion blower side) B
OK (Seatback blower side) C

REPLACE SEAT CUSHION BLOWER

REPLACE SEATBACK BLOWER

A

4.CHECK WIRE HARNESS (A/C AMPLIFIER ASSEMBLY - SEAT CLIMATE CONTROL BLOWER)

Disconnect the J59, U12 and U13 connectors.

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

Resistance:
LHD models:
Tester Connection Condition Specified Condition
J59-16 (LOUT) - U12-3 (SIGN) Always Below 1 Ω
J59-16 (LOUT) - U13-3 (FCTB) Always Below 1 Ω
J59-16 (LOUT) - Body ground Always 10 kΩ or higher
RHD models:
Tester Connection Condition Specified Condition
J59-8 (LOUT) - U12-3 (SIGN) Always Below 1 Ω
J59-8 (LOUT) - U13-3 (FCTB) Always Below 1 Ω
J59-8 (LOUT) - Body ground Always 10 kΩ or higher

REPAIR OR REPLACE WIRE HARNESS

OK

5.CHECK WIRE HARNESS (SEAT HEATER SWITCH)

Disconnect the J45 connector.

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

Resistance:
Tester Connection Condition Specified Condition
J45-12 (E) - Body ground Always Below 1 Ω

Voltage:
Tester Connection Condition Specified Condition
J45-5 (IG) - Body ground Engine switch on (IG) 10 to 14 V

REPAIR OR REPLACE WIRE HARNESS

OK

6.INSPECT SEAT HEATER SWITCH

Disconnect the J45 switch.

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

Resistance:
Tester Connection Condition Specified Condition
J45-8 (ASS5) - J45-10 (SGND) Always Below 1 kΩ
J45-9 (LH) - J45-10 (SGND) Blower switch OFF Below 1.1 kΩ
Blower switch ON (Vol: 3) Below 111 Ω

REPLACE SEAT HEATER SWITCH

OK

7.CHECK WIRE HARNESS (SEAT HEATER SWITCH - A/C AMPLIFIER ASSEMBLY)

Disconnect the J45 and J59 connectors.

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

(*): RHD models

Resistance:

Tester Connection	Condition	Specified Condition
J45-8 (ASS5) - J59-7 (S5-4)	Always	Below 1 Ω
LHD models: J45-9 (LH) - J59-3 (SW-4)	Always	Below 1 Ω
RHD models: J45-9 (LH) - J59-2 (SW-4)	Always	Below 1 Ω
J45-10 (SGND) - J59-10 (SG-4)	Always	Below 1 Ω
J45-12 (E) - Body ground	Always	Below 1 Ω
J45-8 (ASS5) - Body ground	Always	10 kΩ or higher
J45-9 (LH) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE WIRE HARNESS

REPLACE A/C AMPLIFIER ASSEMBLY

8.CHECK WIRE HARNESS

Disconnect the T12 connector.

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

Resistance:
Tester Connection Condition Specified Condition
T12-4 (GND) - Body ground Always Below 1 Ω

Voltage:
Tester Connection Condition Specified Condition
T12-1 (IG) - Body ground Engine switch on (IG) 10 to 14 V

Reconnect the T12 connector.

Disconnect the T13 connector.

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

Resistance:
Tester Connection Condition Specified Condition
T13-1 (GND) - Body ground Always Below 1 Ω

Voltage:
Tester Connection Condition Specified Condition
T13-2 (IG) - Body ground Engine switch on (IG) 10 to 14 V

REPAIR OR REPLACE WIRE HARNESS

OK

9.INSPECT SEAT CLIMATE CONTROL BLOWER

Check the input signal waveform.

Connect the oscilloscope to terminal 3 and body ground with the climate control blower connector still connected.

Check the signal waveform according to the condition(s) in the table below.

Item	Condition
Tool setting	2 V/DIV., 500 μsec/DIV.,
Vehicle condition	Engine switch on (IG), seat heater switch ON

OK:
The waveform is displayed as shown in the illustration.

Result:
NG A
OK (Seat cushion blower side) B
OK (Seatback blower side) C

REPLACE SEAT CUSHION BLOWER

REPLACE SEATBACK BLOWER

A

10.CHECK WIRE HARNESS (A/C AMPLIFIER ASSEMBLY - SEAT CLIMATE CONTROL BLOWER)

Disconnect the J59, T12 and T13 connectors.

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

Resistance:
LHD models:
Tester Connection Condition Specified Condition
J59-8 (ROUT) - T12-3 (SIGN) Always Below 1 Ω
J59-8 (ROUT) - T13-3 (VSVG) Always Below 1 Ω
J59-8 (ROUT) - Body ground Always 10 kΩ or higher
RHD models:
Tester Connection Condition Specified Condition
J59-16 (ROUT) - T12-3 (SIGN) Always Below 1 Ω
J59-16 (ROUT) - T13-3 (VSVG) Always Below 1 Ω
J59-16 (ROUT) - Body ground Always 10 kΩ or higher

REPAIR OR REPLACE WIRE HARNESS

OK

11.CHECK WIRE HARNESS (SEAT HEATER SWITCH)

Disconnect the J45 connector.

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

Resistance:
Tester Connection Condition Specified Condition
J45-12 (E) - Body ground Always Below 1 Ω

Voltage:
Tester Connection Condition Specified Condition
J45-5 (IG) - Body ground Engine switch on (IG) 10 to 14 V

REPAIR OR REPLACE WIRE HARNESS

OK

12.INSPECT SEAT HEATER SWITCH

Disconnect the J45 switch.

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

Resistance:
Tester Connection Condition Specified Condition
J45-8 (ASS5) - J45-10 (SGND) Always Below 1 kΩ
J45-7 (RH) - J45-10 (SGND) Blower switch OFF Below 1.1 kΩ
Blower switch ON (Vol: 3) Below 111 Ω

REPLACE SEAT HEATER SWITCH

OK

13.CHECK WIRE HARNESS (SEAT HEATER SWITCH - A/C AMPLIFIER ASSEMBLY)

Disconnect the J45 and J59 connectors.

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

(*): RHD models

Resistance:

Tester Connection	Condition	Specified Condition
LHD models: J45-7 (RH) - J59-2 (SW-5)	Always	Below 1 Ω
RHD models: J45-7 (RH) - J59-3 (SW-5)	Always	Below 1 Ω
J45-8 (ASS5) - J59-7 (S5-4)	Always	Below 1 Ω
J45-10 (SGND) - J59-10 (SG-4)	Always	Below 1 Ω
J45-12 (E) - Body ground	Always	Below 1 Ω
J45-7 (RH) - J59-2 (SW-5)	Always	10 kΩ or higher
J45-8 (ASS5) - J59-7 (S5-4)	Always	10 kΩ or higher

REPAIR OR REPLACE WIRE HARNESS

REPLACE A/C AMPLIFIER ASSEMBLY

14.CHECK WIRE HARNESS

Disconnect the U12 (T12) connector.

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

*1: Front LH

*2: Front RH

Resistance:
Front LH:
Tester Connection Condition Specified Condition
U12-4 (GND) - Body ground Always Below 1 Ω
Front RH:
Tester Connection Condition Specified Condition
T12-4 (GND) - Body ground Always Below 1 Ω

Voltage:
Front LH:
Tester Connection Condition Specified Condition
U12-1 (IG) - Body ground Engine switch on (IG) 10 to 14 V
Front RH:
Tester Connection Condition Specified Condition
T12-4 (GND) - Body ground Always Below 1 Ω

Reconnect the U12 (T12) connector.

Disconnect the U13 (T13) connector.

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

*1: Front LH

*2: Front RH

Resistance:
Front LH:
Tester Connection Condition Specified Condition
U13-1 (GND) - Body ground Always Below 1 Ω
Front RH:
Tester Connection Condition Specified Condition
T13-1 (GND) - Body ground Always Below 1 Ω

Voltage:
Front LH:
Tester Connection Condition Specified Condition
U13-2 (IG) - Body ground Engine switch on (IG) 10 to 14 V
Front RH:
Tester Connection Condition Specified Condition
U13-2 (IG) - Body ground Engine switch on (IG) 10 to 14 V

REPAIR OR REPLACE WIRE HARNESS

OK

15.INSPECT SEAT CLIMATE CONTROL BLOWER

Check the input signal waveform.

Connect the oscilloscope to terminal 3 and body ground with the climate control blower connector still connected.

Check the signal waveform according to the condition(s) in the table below.

Item	Condition
Tool setting	2 V/DIV., 500 μsec/DIV.,
Vehicle condition	Engine switch on (IG), seat heater switch ON

OK:
The waveform is displayed as shown in the illustration.

*1: Front LH

*2: Front RH

Result:
NG A
OK (Seat cushion blower side) B
OK (Seatback blower side) C

REPLACE SEAT CUSHION BLOWER

REPLACE SEATBACK BLOWER

A

16.CHECK WIRE HARNESS (A/C AMPLIFIER ASSEMBLY - SEAT CLIMATE CONTROL BLOWER)

Disconnect the J59, U12 (T12) and U13 (T13) connectors.

*1: Front LH

*2: Front RH

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

Resistance:
Front LH:

Tester Connection	Condition	Specified Condition
RHD models: J59-8 (LOUT) - U12-3 (SIGN)	Always	Below 1 Ω
RHD models: J59-8 (LOUT) - U13-3 (FCTB)	Always	Below 1 Ω
RHD models: J59-8 (LOUT) - Body ground	Always	10 kΩ or higher
LHD models: J59-16 (LOUT) - U12-3 (SIGN)	Always	Below 1 Ω
LHD models: J59-16 (LOUT) - U13-3 (FCTB)	Always	Below 1 Ω
LHD models: J59-16 (LOUT) - Body ground	Always	10 kΩ or higher

Front RH:

Tester Connection	Condition	Specified Condition
LHD models: J59-8 (ROUT) - T12-3 (SIGN)	Always	Below 1 Ω
LHD models: J59-8 (ROUT) - T13-3 (VSVG)	Always	Below 1 Ω
LHD models: J59-8 (ROUT) - Body ground	Always	10 kΩ or higher
RHD models: J59-16 (ROUT) - T12-3 (SIGN)	Always	Below 1 Ω
RHD models: J59-16 (ROUT) - T13-3 (VSVG)	Always	Below 1 Ω
RHD models: J59-16 (ROUT) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE WIRE HARNESS

OK

17.CHECK WIRE HARNESS (SEAT HEATER SWITCH)

Disconnect the J45 connector.

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

Resistance:
Tester Connection Condition Specified Condition
J45-12 (E) - Body ground Always Below 1 Ω

Voltage:
Tester Connection Condition Specified Condition
J45-5 (IG) - Body ground Engine switch on (IG) 10 to 14 V

REPAIR OR REPLACE WIRE HARNESS

OK

18.INSPECT SEAT HEATER SWITCH

Disconnect the J45 switch.

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

Resistance:
Front LH:
Tester Connection Condition Specified Condition
J45-8 (ASS5) - J45-10 (SGND) Always Below 1 kΩ
J45-9 (LH) - J45-10 (SGND) Blower switch OFF Below 1.1 kΩ
Blower switch ON (Vol: 3) Below 111 Ω
Front RH:
Tester Connection Condition Specified Condition
J45-8 (ASS5) - J45-10 (SGND) Always Below 1 kΩ
J45-7 (RH) - J45-10 (SGND) Blower switch OFF Below 1.1 kΩ
Blower switch ON (Vol: 3) Below 111 Ω

REPLACE SEAT HEATER SWITCH

OK

19.CHECK WIRE HARNESS (SEAT HEATER SWITCH - A/C AMPLIFIER ASSEMBLY)

Disconnect the J45 and J59 connectors.

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

(*): RHD models

Resistance:
Front LH:

Tester Connection	Condition	Specified Condition
J45-8 (ASS5) - J59-7 (S5-4)	Always	Below 1 Ω
LHD models: J45-9 (LH) - J59-3 (SW-4)	Always	Below 1 Ω
RHD models: J45-9 (LH) - J59-2 (SW-4)	Always	Below 1 Ω
J45-10 (SGND) - J59-10 (SG-4)	Always	Below 1 Ω
J45-12 (E) - Body ground	Always	Below 1 Ω
J45-8 (ASS5) - Body ground	Always	10 kΩ or higher
J45-9 (LH) - Body ground	Always	10 kΩ or higher

Front RH:

Tester Connection	Condition	Specified Condition
LHD models: J45-7 (RH) - J59-2 (SW-5)	Always	Below 1 Ω
RHD models: J45-7 (RH) - J59-3 (SW-5)	Always	Below 1 Ω
J45-8 (ASS5) - J59-7 (S5-4)	Always	Below 1 Ω
J45-10 (SGND) - J59-10 (SG-4)	Always	Below 1 Ω
J45-12 (E) - Body ground	Always	Below 1 Ω
J45-7 (RH) - Body ground	Always	10 kΩ or higher
J45-8 (ASS5) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE WIRE HARNESS

REPLACE A/C AMPLIFIER ASSEMBLY

LEXUS IS250, IS220d / GSE20 ALE20

SEAT

Lexus IS250 IS220d GSE20 ALE20

CLIMATE CONTROL SEAT SYSTEM

NG	A
OK (Seat cushion blower side)	B
OK (Seatback blower side)	C