2003 LEXUS LS430 replacement

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 circuit controls the amount of the coolant flowing to the heater core by a signal from the A/C amplifier,
and adjusts the temperature at the air outlets.
WIRING DIAGRAM
Fig. 132: Water Valve Control Servomotor Circuit

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

OK:
Water valve lever changes in accordance with each display code.
NG: REPLACE AIR CONDITIONING AMPLIFIER (SEE REPLACEMENT
)
OK: Go to next step
2.INSPECT WATER VALVE SERVOMOTOR
a. Remove the water valve servomotor.
b. Connect the positive (+) lead from the battery to terminal 3 and negative (-) lead to terminal 1, then
check that the lever turns to the "OPEN" position smoothly.
c. Connect the positive (+) lead from the battery to terminal 3 and negative (-) lead to terminal 2, then
check that the lever turns to the "SHUT" position smoothly.
Fig. 134: Inspecting Water Valve Servomotor

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
7OPEN
8OPEN
9OPEN

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 circuit turns the servomotor and changes each damper position by receiving the signals from the A/C
amplifier assy. When the AUTO switch is on, the A/C amplifier changes the mode between "FACE", "BI-
LEVEL" and "FOOT" following the temperature setting.
WIRING DIAGRAM

c. Press the driver temperature up switch, and change to STEP operation.
d. Press the driver temperature up switch, and check the air flow mode by hand.
DISPLAY CODE - AIR FLOW POSITION
OK:
Air flow position changes in accordance with each display code.
NG: REPLACE AIR CONDITIONING AMPLIFIER (SEE REPLACEMENT
)
OK: Go to next step
2.INSPECT AIR VENT MODE CONTROL SERVOMOTOR
a. Remove the vent mode control servomotor.
b. Measure resistance according to the value (s) in the table below:
Standard: (Driver side)
AIR VENT MODE CONTROL SERVOMOTOR (DRIVER SIDE) RESISTANCE
Display codeAir flow position
0FACE
1FACE
2FACE
3FACE
4BI-LEVEL
5BI-LEVEL
6FOOT
7FOOT
8FOOT/DEF
9DEF
Tester connectionConditionSpecified condition
A44-1 (AODr1) -A44-4 (AODB)Always24.3 to 26.3 ohms
A44-2 (AODr2) -A44-4 (AODB)Always24.3 to 26.3 ohms
A44-5 (AODr3) -A44-4 (AODB)Always24.3 to 26.3
A44-6 (AODr4) -A44-4 (AODB)Always24.3 to 26.3

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: REPLACE AIR CONDITIONING AMPLIFIER (SEE REPLACEMENT
)
CIRCUIT DESCRIPTION
This servomotor is controlled by the A/C amplifier. Air flow temperature changes when moving the air mix
damper to the target point. The target point can be detected with the air mix damper position sensor.
WIRING DIAGRAM

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.
NG: REPLACE AIR CONDITIONING AMPLIFIER (SEE REPLACEMENT
)
OK: Go to next step
2.PERFORM ACTUATOR CHECK

a. Set the actuator check mode (see ACTUATOR CHECK
).
b. Press the driver temperature up switch and change to the STEP operation.
c. Check the air flow temperature by hand.
DISPLAY CODE - AIR MIX DAMPER OPERATION
OK:
ItemMeasure Item/Display (Range)Normal ConditionDiagnostic
Note
AIR MIX
STEP-DAir mix servomotor target STEP (Driver
side) / min.: 257 STEP max.: 1571 STEPMAX COOL: Approx. 257 STEP
MAX HOT: Approx. 1,571 STEP-
AIR MIX
STEP-PAir mix servomotor target STEP
(Passenger side) / min.: 257 STEP max.:
1571 STEPMAX COOL: Approx. 257 STEP
MAX HOT: Approx. 1,571 STEP-
Display CodeAir Mix Damper Operation
0COOL side (0 % open)
1COOL side (0 % open)
2COOL side (0 % open)
3COOL side (0 % open)
4COOL/HOT (50 % open)
5COOL/HOT (50 % open)
6COOL/HOT (50 % open)
7HOT side (100% open)
8HOT side (100% open)
9HOT side (100% open)

Air flow temperature changes in accordance with each display code.
NG: REPLACE AIR CONDITIONING AMPLIFIER (SEE REPLACEMENT
)
OK: Go to next step
3.INSPECT AIR MIX CONTROL SERVOMOTOR
a. Remove the air mix control servomotor.
b. Measure the resistance according to the value (s) in the table below:
Standard: (Driver side)
AIR MIX CONTROL SERVOMOTOR RESISTANCE (DRIVER'S SIDE)
Tester connectionConditionSpecified condition
A42-1 (AMDr1) -A42-4 (AMDB)Always24.3 to 26.3 ohms
A42-2 (AMDr2) -A42-4 (AMDB)Always24.3 to 26.3 ohms
A42-5 (AMDr3) -A42-4 (AMDB)Always24.3 to 26.3 ohms
A42-6 (AMDr4) -A42-4 (AMDB)Always24.3 to 26.3 ohms

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 is the back-up power source circuit for the A/C amplifier. Power is supplied even when turning the ignition
switch off and is used for diagnostic trouble code memory, etc.
WIRING DIAGRAM
Fig. 146: Back
-Up Power Source Circuit