2003 LEXUS LS430 heater

Fig. 45: Climate Control Does Not Operate (Blinking Pattern 4) Wiring Diagram (2 Of 2)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.CHECK SEAT HEATER (INDICATOR)
a. Check that the climate control indicator is blinking.
Result:

RESULT REFERENCE
B: Go to step 5
A: Go to next step
2.INSPECT FRONT SEAT HEATER SWITCH (THERMISTOR OF SEATBACK) (SEE
INSPECTION
)
NG: REPLACE FRONT SEAT HEATER SWITCH
OK: Go to next step
3.CHECK WIRE HARNESS (SEAT CLIMATE CONTROL BLOWER (CLIMATE CONTROL
ECU) - SEAT CLIMATE CONTROLLER (SEATBACK))
HINT:
When the driver side indicator is blinking, check the driver side connector. When the passenger side
indicator is blinking, check the passenger side connector.
a. Disconnect the C20 or C21 blower connector.
b. Disconnect the S34 or S35 controller connector.
c. Measure the resistance of the wire harness side connectors.
Standard:
Driver side
TESTER CONNECTION AND SPECIFIED CONDITION - DRIVER SIDE
Passenger side
TESTER CONNECTION AND SPECIFIED CONDITION - PASSENGER SIDE
ResultProceed to
Front climate control switch indicator is blinkingA
Rear climate control switch indicator is blinkingB
Tester ConnectionSpecified Condition
C20-3 (TBS) - S34-2 (TBS)Below 1 ohms
C20-4 (TB5) - S34-3 (TB5)Below 1 ohms
Tester ConnectionSpecified Condition
C21-3 (TBS) - S35-2 (TBS)Below 1 ohms
C21-4 (TB5) - S35-3 (TB5)Below 1 ohms

Fig. 47: Identifying Seat Climate Controller Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPLACE FRONT SEAT HEATER SWITCH
OK: REPLACE SEAT CLIMATE CONTROL CONTROLLER
5.INSPECT REAR SEAT HEATER SWITCH (THERMISTOR OF SEATBACK) (SEE
INSPECTION
)
NG: REPLACE FRONT SEAT HEATER SWITCH
OK: Go to next step
6.CHECK WIRE HARNESS (SEAT CLIMATE CONTROL BLOWER (CLIMATE CONTROL
ECU) - SEAT CLIMATE CONTROLLER)
HINT:

Fig. 48: Identifying Seat Climate Control Blower Connector Terminals And Seat Climate
Controller Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS AND CONNECTOR
OK: Go to next step
7.INSPECT SEAT CLIMATE CONTROL CONTROLLER (THERMISTOR OF SEAT CUSHION)
(SEE INSPECTION
)
NG: REPLACE FRONT SEAT HEATER SWITCH
OK: Go to next step
8.CHECK WIRE HARNESS (SEAT CLIMATE CONTROL BLOWER (CLIMATE CONTROL
ECU) - SEAT CLIMATE CONTROLLER)
HINT:
When the rear LH indicator is blinking, check the rear LH side connector. When the rear RH indicator is
blinking, check the rear right RH side connector.
a. Disconnect the C28 or C30 blower connector.
b. Disconnect the S53 or S55 controller connector.
c. Measure the resistance of the wire harness side connectors.
Standard:
Rear LH
TESTER CONNECTION AND SPECIFIED CONDITION - REAR LH
Rear RH
TESTER CONNECTION AND SPECIFIED CONDITION - REAR RH
Tester ConnectionSpecified Condition
C28-6 (TC5) - S53-3 (TC5)Below 1 ohms
C28-15 (TCS) - S53-2 (TCS)Below 1 ohms
Tester ConnectionSpecified Condition
C30-6 (TC5) - S55-3 (TC5)Below 1 ohms
C30-15 (TCS) - S55-2 (TCS)Below 1 ohms

Fig. 49: Identifying Seat Climate Control Blower Connector Terminals And Seat Climate
Controller Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS AND CONNECTOR
OK: Go to next step
9.INSPECT SEAT HEATER (THERMISTOR) (SEE INSPECTION
)
NG: REPLACE SEAT CUSHION PAD
OK: Go to next step
10.CHECK WIRE HARNESS (SEAT CLIMATE CONTROL BLOWER (CLIMATE CONTROL
ECU) - SEAT HEATER)
HINT:
When the rear LH indicator is blinking, check the rear LH side connector. When the rear RH indicator is
blinking, check the rear right RH side connector.
a. Disconnect the C28 or C30 blower connector.
b. Disconnect the S60 or S61 controller connector.
c. Measure the resistance of the wire harness side connectors.
Standard:
Rear LH
TESTER CONNECTION AND SPECIFIED CONDITION - REAR LH
Rear RH
TESTER CONNECTION AND SPECIFIED CONDITION - REAR RH
Tester ConnectionSpecified Condition
C28-5 (H5) - S60-2 (H5)Below 1 ohms
C28-14 (HS) - S60-4 (HS)Below 1 ohms
Tester ConnectionSpecified Condition
C30-5 (H5) - S61-2 (H5)Below 1 ohms
C30-14 (HS) - S61-4 (HS)Below 1 ohms

Fig. 50: Identifying Seat Climate Control Blower Connector Terminals And Seat Heater Connector
Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS AND CONNECTOR
OK: REPLACE SEAT CLIMATE CONTROL CONTROLLER (CLIMATE CONTROL ECU)
CIRCUIT DESCRIPTION
If the air duct is loose or torn, the air filter is extremely clogged or if the fan motor's performance deteriorates,
the air passing by the Peltier element of the seat climate controller may decrease as a result. If this happens, the
thermistor will frequently lose control and the surface of the seat will not become sufficiently cool or warm.
INSPECTION PROCEDURE
1.CHECK HEATER AIR FILTER
a. Remove the air filter.
b. Check the air filter.
OK: The air filter should not be clogged.
c. Check the air flow volume.
OK: Sufficient volume of air should be delivered from the air filter.
NG: CLEAN OR REPLACE HEATER AIR FILTER
OK: Go to next step
2.CHECK CLIMATE CONTROL FAN MOTOR
a. Check fan motor speed operation.
OK: The fan motor should turn smoothly.
NG: REPLACE SEAT CLIMATE CONTROL BLOWER
OK: Go to next step
3.CHECK AIR DUCT
a. Check air duct connection condition.
OK: The duct should not be loosened and disconnected.

Fig. 73: Identifying L14 Luggage Room J/B ECU Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPLACE LUGGAGE ROOM JUNCTION BLOCK ASSY
OK: REPLACE LUGGAGE ROOM JUNCTION BLOCK ECU
10.INSPECT REAR SEAT HEATER SWITCH
a. Disconnect the C31 switch connector.
b. Measure the resistance of the switch.
Standard:
TESTER CONNECTION AND SPECIFIED CONDITION
Tester ConnectionSwitch ConditionSpecified Condition
11 (SWL) - 8 (E)OFF10 kohms or higher
11 (SWL) - 8 (E)ONBelow 1 ohms
4 (SWR) - 8 (E)OFF10 kohms or higher

Fig. 74: Identifying Climate Control Switch Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPLACE REAR SEAT HEATER SWITCH
OK: Go to next step
11.CHECK WIRE HARNESS (CLIMATE CONTROL SWITCH - BODY GROUND)
a. Disconnect the C31 switch connector.
b. Measure the resistance of the wire harness side connector.
Standard:
TESTER CONNECTION AND SPECIFIED CONDITION
4 (SWR) - 8 (E)ONBelow 1 ohms
Tester ConnectionSpecified Condition
C31-8 (E) - Body groundBelow 1 ohms