2003 LEXUS LS430 air conditioning

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
The pressure switch sends the appropriate signals to the A/C amplifier when the A/C refrigerant pressure drops
too low or rises too high.
When the A/C amplifier receives these signals, the compressor does not compress refrigerant.
Fig. 75: DTC Detection Item Trouble Area Chart

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

Fig. 78: Refrigerant Volume Problem Symptoms Chart
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
*: Bubbles in the sight glass with ambient temperature higher than usual can be considered normal if
cooling is sufficient.
NG: CHARGE REFRIGERANT (SEE ON
-VEHICLE INSPECTION )
OK: Go to next step
2.INSPECT AIR CONDITIONING AMPLIFIER (PRS, SG-5)
a. Remove the A/C amplifier with connector still connected.
b. Install the manifold gauge set (see ON
-VEHICLE INSPECTION ).
c. Turn the ignition switch to the ON position.
d. Measure the voltage according to the value (s) in the table below.
OK:
The voltage depends on the refrigerant pressure as shown in the chart.

Fig. 79: Inspecting Air Conditioning Amplifier (PRS, SG-5)

NG: REPLACE A/C PRESSURE SENSOR
OK: Go to next step
4.CHECK HARNESS AND CONNECTOR (A/C PRESSURE SENSOR - AIR CONDITIONING
AMPLIFIER) (SEE ELECTRONIC CIRCUIT INSPECTION PROCEDURE
)
a. Measure the resistance according to the value (s) in the table below.
Standard:
A/C PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER RESISTANCE
Tester connectionConditionSpecified condition
A3-2 - A12-17 (PRS)AlwaysBelow 1 ohms
A3-3 - A12-15 (S5-2)AlwaysBelow 1 ohms
A3-1 - A13-12 (SG-5)AlwaysBelow 1 ohms
A12-17 (PRS) - Body groundAlways10 kohms or higher
A12-15 (S5-2) - Body groundAlways10 kohms or higher
A13-12 (SG-5) - Body groundAlways10 kohms or higher

Fig. 81: Checking Harness And Connector (A/C Pressure Sensor -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
A photodiode in the A/C solar sensor detects solar radiation and sends signals to the A/C amplifier.

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:
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 (TSDr)
a. Remove the A/C amplifier with connector 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 (TSDR) VOLTAGE
HINT:
As the inspection light is moved away from the sensor, the voltage increases.
ItemMeasure Item/Display (Range)Normal ConditionDiagnostic
Note
SOLAR SENS-
DSolar sensor (Driver side) / min.: 0 max.:
255Increases as brightness
increases-
NGA
OK (Checking from the PROBLEM SYMPTOM TABLE)B
OK (Checking from the DTC)C
Tester connectionConditionSpecified condition
A11-19 (TSDr) - Body groundSensor is subjected to electric light4.0 to 4.6 V
A11-19 (TSDr) - Body groundSensor is covered by a clothBelow 0.8 V

Use an incandescent lamp for inspection. Bring it within 30 cm (11.8 in.) of the A/C solar sensor.
Result:
AIR CONDITIONING AMPLIFIER (TSDR) TEST RESULT
Fig. 84: Inspecting Air Conditioning Amplifier (TSDR)

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 A/C SOLAR SENSOR
a. Remove the A/C solar sensor.
NGA
OK (Checking from the PROBLEM SYMPTOMS TABLE)B
OK (Checking from the DTC)C

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
A photodiode in the A/C solar sensor detects solar radiation and sends signals to the A/C amplifier.
Fig. 87: Photodiode Resistance/Solar Radiation Strength Graph