2003 LEXUS LS430 Temperature sensor

Fig. 38: Resistance/Temperature Graph
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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)
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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

Temperature Sensor)Thermistor)
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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

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WIRING DIAGRAM

Fig. 42: Ambient Temperature Sensor Circuit
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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-

ECM (TAM - E2) TEST RESULT
B: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
C: REPLACE ECM (SEE REPLACEMENT )
A: Go to next step
3.INSPECT A/C AMBIENT TEMPERATURE SENSOR
a. Remove the A/C ambient temperature sensor.
b. Measure the resistance according to the value (s) in the table below.
Fig. 44: Identifying Terminals Of A/C Ambient Temperature Sensor Connector

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NGA
OK (Checking from the PROBLEM SYMPTOM TABLE)B
OK (Checking from the DTC)C

Standard:
A/C AMBIENT TEMPERATURE SENSOR RESISTANCE
HINT:
As the temperature increases, the resistance decreases (see the graph below).
Fig. 45: Resistance/Temperature Graph
Tester connectionConditionSpecified condition
A1-1 - A1-210°C (50°F)3.00 to 3.73 kohms
A1-1 - A1-215°C (59°F)2.45 to 2.88 kohms
A1-1 - A1-220°C (68°F)1.95 to 2.30 kohms
A1-1 - A1-225°C (77°F)1.60 to 1.80 kohms
A1-1 - A1-230°C (86°F)1.28 to 1.47 kohms
A1-1 - A1-235°C (95°F)1.00 to 1.22 kohms
A1-1 - A1-240°C (104°F)0.80 to 1.00 kohms
A1-1 - A1-245°C (113°F)0.65 to 0.85 kohms
A1-1 - A1-250°C (122°F)0.50 to 0.70 kohms
A1-1 - A1-255°C (131°F)0.44 to 0.60 kohms
A1-1 - A1-260°C (140°F)0.36 to 0.50 kohms

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NG: REPLACE A/C AMBIENT TEMPERATURE SENSOR
OK: Go to next step
4.CHECK HARNESS AND CONNECTOR (ECM-A/C AMBIENT TEMPERATURE SENSOR)
(SEE ELECTRONIC CIRCUIT INSPECTION PROCEDURE
)
a. Measure the resistance according to the value (s) in the table below.
Standard:
ECM-A/C AMBIENT TEMPERATURE SENSOR RESISTANCE
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
Tester connectionConditionSpecified condition
E3-18 (TAM) - A1-1AlwaysBelow 1 ohms
E5-28 (E2) - A1-2AlwaysBelow 1 ohms
E3-18 (TAM) - Body groundAlways10 kohms or higher
E5-28 (E2) - Body groundAlways10 kohms or higher

Fig. 46: Checking Harness And Connector (ECM-A/C Ambient Temperature Sensor)
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