2003 LEXUS LS430 air condition

a. Remove the cool air bypass servomotor.
b. Measure the resistance according to the value (s) in the table below.
Standard:
COOL AIR BYPASS SERVOMOTOR RESISTANCE
c. Measure the resistance according to the value (s) in the table below.
HINT:
SEE COOL AIR BYPASS DAMPER CONTROL SERVOMOTOR CIRCUIT (DRIVER SIDE)
for
operation procedure for the cool air bypass servomotor.
Standard:
COOL AIR BYPASS SERVOMOTOR RESISTANCE
HINT:
As the cool air bypass servomotor moves from the cool side to the hot side, the resistance decreases
gradually without interruption.
Tester connectionConditionSpecified condition
C24-1 (VZ) - C24-2 (GND)Always4.2 to 7.2 kohms
Tester connectionConditionSpecified condition
C24-3 (PT) - C24-2 (GND)Max. Cool3.33 to 4.03 kohms
C24-3 (PT) - C24-2 (GND)Max. Hot0.80 to 1.60 kohms

Fig. 103: Inspecting Cool Air Bypass Servomotor
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPLACE COOL AIR BYPASS SERVOMOTOR
OK: Go to next step
4.CHECK HARNESS AND CONNECTOR (COOL AIR BYPASS SERVOMOTOR - AIR
CONDITIONING AMPLIFIER) (SEE ELECTRONIC CIRCUIT INSPECTION PROCEDURE
)
a. Measure the resistance according to the value (s) in the table below.
Standard:
COOL AIR BYPASS SERVOMOTOR - AIR CONDITIONING AMPLIFIER RESISTANCE
Tester connectionConditionSpecified condition
A36-24 (TPBDr) - C24-3 (PT)AlwaysBelow 1 ohms
A36-11 (S5-5) - C24-1 (VZ)AlwaysBelow 1 ohms
A36-15 (SG-7) - C24-2 (GND)AlwaysBelow 1 ohms
C24-3 (PT) - Body groundAlways10 kohms or higher
C24-1 (VZ) - Body groundAlways10 kohms or higher

Fig. 104: Checking Harness And Connector (Cool Air Bypass Servomotor - Air Conditioning
Amplifier)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: REPLACE AIR CONDITIONING AMPLIFIER (SEE REPLACEMENT
)
CIRCUIT DESCRIPTION
This sensor detects the position of the cool air bypass servomotor (Max cool damper servomotor) and sends the
appropriate si
gnals to the A/C amplifier. The position sensor is built in the cool air bypass servomotor.

Fig. 107: Max Cool Damper Position Sensor Circuit (Passenger Side)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.READ VALUE ON HAND-HELD TESTER
a. Connect the hand-held tester to the DLC3.
b. Turn the ignition switch to the ON position and push the hand-held tester main switch on.
c. Select the item below in the DATA LIST, and read the display on the hand-held tester.
DATA LIST / AIR CONDITIONER:
DATA LIST / AIR CONDITIONER
ItemMeasure Item/Display (Range)Normal ConditionDiagnostic
Note
A/B DAMP
POS-PCool air bypass damper position (Passenger
side) / min.: -14% max.: 113.5%OPEN: Approx. 0 %
SHUT: Approx. 100%-

OK:
The display is as specified in the normal condition.
Result:
AIR CONDITIONER TEST RESULT
B: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
C: REPLACE AIR CONDITIONING AMPLIFIER (SEE REPLACEMENT )
A: Go to next step
2.INSPECT AIR CONDITIONING AMPLIFIER (TPBPa - SG (SG-7))
a. Remove the A/C amplifier with connectors still connected.
b. Turn the ignition switch to the ON position.
c. Change the set temperature to activate the cool air bypass servomotor.
d. Measure the voltage according to the value (s) in the table below.
Standard:
AIR CONDITIONING AMPLIFIER (TPBPA - SG (SG-7) VOLTAGE
HINT:
As the set temperature increases, the voltage decreases gradually without interruption.
Result:
AIR CONDITIONING AMPLIFIER (TPBPA - SG (SG-7) TEST RESULT
NGA
OK (Checking from the PROBLEM SYMPTOM TABLE)B
OK (Checking from the DTC)C
Tester connectionConditionSpecified condition
A37-21 (TPBPa) - A38-19 (SG)MAX. Hot0.5 to 1.8 V
A37-21 (TPBPa) - A38-19 (SG)MAX. Cool3.5 to 4.5 V
NGA
OK (Checking from the PROBLEM SYMPTOMS TABLE)B
OK (Checking from the DTC)C

Fig. 108: Inspecting Air Conditioning Amplifier (TPBPA - SG (SG-7)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
B: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
C: REPLACE AIR CONDITIONING AMPLIFIER (SEE REPLACEMENT )
A: Go to next step
3.INSPECT COOL AIR BYPASS SERVOMOTOR
a. Remove the cool air bypass servomotor.
b. Measure the resistance according to the value (s) in the table below.
Standard:
COOL AIR BYPASS SERVOMOTOR RESISTANCE
c. Measure the resistance accordin
g to the value (s) in the table below.
Tester connectionConditionSpecified condition
C25-1 (VZ) - C25-2 (GND)Always4.2 to 7.2 kohms

HINT:
SEE COOL AIR BYPASS DAMPER CONTROL SERVOMOTOR CIRCUIT (PASSENGER
SIDE) for operation procedure for cool air bypass servomotor.
Standard:
COOL AIR BYPASS SERVOMOTOR RESISTANCE
HINT:
As the cool air bypass servomotor moves from the cool side to the hot side, the resistance decreases
gradually without interruption.
Fig. 109: Inspecting Cool Air Bypass Servomotor

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPLACE COOL AIR BYPASS SERVOMOTOR
Tester connectionConditionSpecified condition
C25-3 (PT) - C25-2 (GND)Max. Cool3.33 to 4.03 kohms
C25-3 (PT) - C25-2 (GND)Max. Hot0.80 to 1.60 kohms

OK: Go to next step
4.CHECK HARNESS AND CONNECTOR (COOL AIR BYPASS SERVOMOTOR - AIR
CONDITIONING AMPLIFIER) (SEE ELECTRONIC CIRCUIT INSPECTION PROCEDURE
)
a. Measure the resistance according to the value (s) in the table below.
Standard:
COOL AIR BYPASS SERVOMOTOR - AIR CONDITIONING AMPLIFIER RESISTANCE
Tester connectionConditionSpecified condition
A37-21 (TPBPa) - C25-3 (PT)AlwaysBelow 1 ohms
A37-18 (S5-3) - C25-1 (VZ)AlwaysBelow 1 ohms
A37-19 (SG) - C25-2 (GND)AlwaysBelow 1 ohms
C25-3 (PT) - Body groundAlways10 kohms or higher
C25-1 (VZ) - Body groundAlways10 kohms or higher
C25-2 (GND) - Body groundAlways10 kohms or higher