2003 LEXUS LS430 climate control

Fig. 29: Climate Control Does Not Operate (Blinking Pattern 2) Wiring Diagram
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.INSPECT FRONT SEAT HEATER SWITCH (INDICATOR)
a. Check that the climate control indicator is blinkin
g.

Result:
RESULT REFERENCE
B: Go to step 4
A: Go to next step
2.INSPECT FRONT SEAT HEATER SWITCH (FRONT) (SEE INSPECTION
)
NG: REPLACE CLIMATE CONTROL SWITCH
OK: Go to next step
3.CHECK WIRE HARNESS (SEAT CLIMATE CONTROL BLOWER (CLIMATE CONTROL
ECU) - CLIMATE CONTROL SWITCH)
HINT:
When the indicator of driver's side is blinking, check the driver's side connector. When the indicator of
passenger's side is blinking, check the passenger's side connector.
a. Disconnect the C20 or C21 blower connector.
b. Measure the resistance of the wire harness side connector.
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 ConnectionConditionSpecified Condition
C20-12 (VS) - C20-13 (V5)MAX. WARM --> MAX. COOL0 --> 5 kohms
C20-9 (VG) - C20-12 (VS)MAX. COOL --> MAX. WARM0 --> 5 kohms
Tester ConnectionConditionSpecified Condition
C21-12 (VS) - C21-13 (V5)MAX. WARM --> MAX. COOL0 --> 5 kohms
C21-9 (VG) - C21-12 (VS)MAX. COOL --> MAX. WARM0 --> 5 kohms

Fig. 30: Identifying Seat Climate Control Blower Connector Terminals And Climate Control
Switch Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS AND CONNECTOR
OK: REPLACE SEAT CLIMATE CONTROL BLOWER (CLIMATE CONTROL ECU)
4.INSPECT CLIMATE CONTROL SWITCH (SEE INSPECTION
)
NG: REPLACE CLIMATE CONTROL SWITCH
OK: Go to next step
5.CHECK WIRE HARNESS (SEAT CLIMATE CONTROL BLOWER (CLIMATE CONTROL
ECU) - CLIMATE CONTROL SWITCH)
HINT:
When the indicator of rear left side is blinking, check the rear left side connector. When the indicator of

Fig. 31: Identifying Seat Climate Control Blower Connector Terminals And Climate Control
Switch Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS AND CONNECTOR
OK: REPLACE SEAT CLIMATE CONTROL BLOWER (CLIMATE CONTROL ECU)
CIRCUIT DESCRIPTION
As a result of an short circuit, the ECU may not be able to provide 5 V of power voltage to the seat climate
controller thermistor circuit, climate control switch's volume control circuit or rear seat heater thermistor circuit.
If this happens, all output will be stopped and the indicator illuminates according to blinking pattern 3.
WIRING DIAGRAM

Fig. 32: Climate Control Does Not Operate (Blinking Pattern 3) Wiring Diagram (1 Of 2)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

Fig. 33: Climate Control Does Not Operate (Blinking Pattern 3) 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 8
A: Go to next step
2.INSPECT FRONT SEAT HEATER SWITCH (FRONT) (SEE INSPECTION
)
NG: REPLACE CLIMATE CONTROL SWITCH
OK: Go to next step
3.CHECK WIRE HARNESS (SEAT CLIMATE CONTROL BLOWER (CLIMATE CONTROL
ECU) - CLIMATE CONTROL SWITCH)
HINT:
a. Disconnect the C20 or C21 blower connector.
b. Measure the resistance of the wire harness side connector.
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
C20-13 (V5) - C20-9 (VG)Approx. 5 kohms
Tester ConnectionSpecified Condition
C21-13 (V5) - C21-9 (VG)Approx. 5 kohms

Fig. 34: Identifying Seat Climate Control Blower Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS AND CONNECTOR
OK: Go to next step
4.CHECK WIRE HARNESS (SEAT CLIMATE CONTROL BLOWER (CLIMATE CONTROL
ECU) - BODY GROUND)
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. Measure the voltage of the wire harness side connector.
Standard:
Driver side