2003 LEXUS LS430 air conditioning

Fig. 148: Inspecting Air Conditioning Amplifier (B - Body Ground)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS
TABLE
CIRCUIT DESCRIPTION
The main power source is supplied to the A/C amplifier when the ignition switch is turned to the ON position.
The power source supplied is used for operating the A/C amplifier and servomotor, etc.
WIRING DIAGRAM

FUSE (P-IG) RESISTANCE
NG: CHECK FOR SHORT IN ALL HARNESSES AND COMPONENTS CONNECTED TO
FAILURE FUSE
OK: Go to next step
2.INSPECT AIR CONDITIONING AMPLIFIER (IG - GND)
a. Remove the A/C amplifier assy 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 (IG - GND) VOLTAGE
NG: Go to STEP 3
Tester itemConditionSpecified condition
P-IG fuseAlwaysBelow 1 ohms
Tester connectionConditionSpecified condition
A11-9 (IG) - 14-1 (GND)Ignition switch ON10 to 14V

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2a0003[- GND)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS
TABLE
3.CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - BATTERY)
(SEE ELECTRONIC CIRCUIT INSPECTION PROCEDURE
)
a. Measure the voltage according to the value (s) in the table below.
Standard:
AIR CONDITIONING AMPLIFIER - BATTERY VOLTAGE
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
Tester connectionConditionSpecified condition
A11-9 (IG) - Body groundIgnition switch OFF --> ONBelow 1.0V --> 10 to 14 V

Fig. 151: Checking Harness And Connector (Air Conditioning Amplifier - Battery)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: Go to next step
4.CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - BODY
GROUND) (SEE ELECTRONIC CIRCUIT INSPECTION PROCEDURE
)
a. Measure the resistance according to the value (s) in the table below.
Standard:
AIR CONDITIONING AMPLIFIER - BODY GROUND RESISTANCE
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
Tester connectionConditionSpecified condition
A11-1 (GND) - Body groundAlwaysBelow 1 ohms

Fig. 152: Checking Harness And Connector (Air Conditioning Amplifier - Body Ground)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: REPLACE AIR CONDITIONING AMPLIFIER (SEE REPLACEMENT
)
CIRCUIT DESCRIPTION
This is the power source for the A/C amplifier and servomotors, etc.
WIRING DIAGRAM

Fig. 153: ACC Power Source Circuit
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.INSPECT AIR CONDITIONING AMPLIFIER (ACC - BODY GROUND)
a. Remove the A/C amplifier assy with connectors still connected.
b. Measure the voltage according to the value (s) in the table below.
Standard:
AIR CONDITIONING AMPLIFIER (ACC - BODY GROUND) VOLTAGE
NG: Go to STEP 2
Tester connectionConditionSpecified condition
A11-3 (ACC) - Body groundTurn the ignition switch to the ACC position10 to 14 V

Fig. 154: Inspecting Air Conditioning Amplifier (ACC - Body Ground)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS
TABLE
2.INSPECT FUSE (P-ACC)
a. Remove the P-ACC fuse from the passenger side J/B.
b. Measure the resistance according to the value (s) in the table below.
Standard:
FUSE (P-ACC) RESISTANCE
NG: CHECK FOR SHORT IN ALL HARNESSES AND COMPONENTS CONNECTED TO
FAILURE FUSE
Tester itemConditionSpecified condition
P-ACC fuseAlwaysBelow 1 ohms

Fig. 155: Identifying Location Of Fuse (P-ACC)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: REPAIR OR REPLACE HARNESS OR CONNECTOR (AIR CONDITIONING
AMPLIFIER - BATTERY)
CIRCUIT DESCRIPTION
The blower motor is operated by signals from the A/C amplifier assy. Blower motor speed signals are
transmitted by changes in the duty ratio.
Duty Ratio
The duty ratio is the ratio of the period of continuity in one cycle. For example, if A is the period of continuity
in one cycle, B is the period of non-continuity.
The blower motor controller controls the blower motor speed.