LEXUS LS430 2003 Factory Repair Manual

Fig. 36: Room Temperature Sensor Circuit
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
OK:
The display is as specified in the normal condition.
Result:
ItemMeasure Item/Display (Range)Normal ConditionDiagnostic
Note
ROOM
TEMPRoom temperature sensor / min.: -6.5°C (20.3°F)
max.: 57.25°C (126.95°F)Actual room temperature
is displayed-

AIR CONDITIONER TEST RESULT
B: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
C: REPLACE AIR CONDITIONING AMPLIFIER (SEE REPLACEMENT )
A
2.INSPECT COOLER (ROOM TEMPERATURE SENSOR) THERMISTOR
a. Remove the cooler (room temperature sensor) thermistor.
b. Measure the resistance according to the value (s) in the table below.
Standard:
COOLER (ROOM TEMPERATURE SENSOR) THERMISTOR RESISTANCE
NGA
OK (Checking from the PROBLEM SYMPTOM TABLE)B
OK (Checking from the DTC)C
Tester connectionConditionSpecified condition
A14-1 - A14-210°C (50°F)3.00 to 3.73 kohms
A14-1 - A14-215°C (59°F)2.45 to 2.88 kohms
A14-1 - A14-220°C (68°F)1.95 to 2.30 kohms
A14-1 - A14-225°C (77°F)1.60 to 1.80 kohms
A14-1 - A14-230°C (86°F)1.28 to 1.47 kohms
A14-1 - A14-235°C (95°F)1.00 to 1.22 kohms
A14-1 - A14-240°C (104°F)0.80 to 1.00 kohms
A14-1 - A14-245°C (113°F)0.65 to 0.85 kohms
A14-1 - A14-250°C (122°F)0.50 to 0.70 kohms
A14-1 - A14-255°C (131°F)0.44 to 0.60 kohms
A14-1 - A14-260°C (140°F)0.36 to 0.50 kohms

Fig. 37: Identifying Terminals Of A14 A/C Room Temperature Sensor Connector
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
HINT:
As the temperature increases, the resistance decreases (see the
graph below).

Fig. 38: Resistance/Temperature Graph
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPLACE COOLER (ROOM TEMPERATURE SENSOR) THERMISTOR
OK: Go to next step
3.INSPECT AIR CONDITIONING AMPLIFIER (TR - SG-2)
a. Remove the A/C amplifier with connectors still connected.
b. Turn the ignition switch to the ON position.
c. Measure the voltage according to the value (s) in the table below.
Standard:
AIR CONDITIONING AMPLIFIER (TR - SG-2) VOLTAGE
HINT:
As the temperature increases, the voltage decreases.
Result:
AIR CONDITIONING AMPLIFIER TEST RESULT
Tester connectionConditionSpecified condition
A13-16 (TR) - A13-9 (SG-2)Ignition switch ON at 25°C (77°F)1.8 to 2.2 V
A13-16 (TR) - A13-9 (SG-2)Ignition switch ON at 40°C (104°F)1.2 to 1.6 V
NGA

B: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
C: REPLACE AIR CONDITIONING AMPLIFIER (SEE REPLACEMENT )
Fig. 39: Inspecting Air Conditioning Amplifier (TR
- SG-2)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
A
4.CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - COOLER
(ROOM TEMPERATURE SENSOR)THERMISTOR) (SEE ELECTRONIC CIRCUIT
INSPECTION PROCEDURE )
a. Measure the resistance according to the value (s) in the table below.
Standard:
AIR CONDITIONING AMPLIFIER - COOLER (ROOM TEMPERATURE SENSOR)
THERMISTOR) RESISTANCE
OK (Checking from the PROBLEM SYMPTOMS TABLE)B
OK (Checking from the DTC)C

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
Tester connectionConditionSpecified condition
A13-16 (TR) - A14-1AlwaysBelow 1 ohms
A13-9 (SG-2) - A14-2AlwaysBelow 1 ohms
A13-16 (TR) - Body groundAlways10 kohms or higher
A13-9 (SG-2) - Body groundAlwaysBelow 1 ohms

Fig. 40: Checking Harness And Connector (Air Conditioning Amplifier - Cooler (Room

Temperature Sensor)Thermistor)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: REPLACE AIR CONDITIONING AMPLIFIER (SEE REPLACEMENT
)
CIRCUIT DESCRIPTION
The sensor connected to the ECM detects fluctuations in the ambient temperature that is used for controlling the
interior temperature. The sensor sends a signal to the A/C amplifier via the ECM.
Fig. 41: DTC Detection Item Trouble Area Chart

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
WIRING DIAGRAM

Fig. 42: Ambient Temperature Sensor Circuit
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:
OK:
The display is as specified in the normal condition.
ItemMeasurement Item/Display (Range)Normal ConditionDiagnostic
Note
AMBI TEMP
SENSAmbient temperature sensor / min.: -23.3°C (-
9.94°F) max.: 65.95°C (150.71 °F)Actual ambient
temperature is displayed-

Result:
AIR CONDITIONER TEST RESULT
B: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
C: REPLACE AIR CONDITIONING AMPLIFIER (SEE REPLACEMENT )
A
2.INSPECT ECM (TAM - E2)
Fig. 43: ECM Connector Wire Harness View

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
a. Remove the ECM with connectors still connected.
b. Turn the ignition switch to the ON position.
c. Measure the voltage according to the value (s) in the table below.
Standard:
ECM (TAM - E2) VOLTAGE
HINT:
As the temperature increases, the voltage decreases.
Result:
NGA
OK (Checking from the PROBLEM SYMPTOM TABLE)B
OK (Checking from the DTC)C
Tester connectionConditionSpecified condition
E3-18 (TAM) - E5-28 (E2)Ignition switch ON at 25°C (77°F)2.0 +/- 0.2V
E3-18 (TAM) - E5-28 (E2)Ignition switch ON at 40°C (104°F)1.4 +/- 0.2 V