2003 LEXUS LS430 relay

HINT:
If DTC C1741 (AIR SUS relay circuit) is displayed, carry out the inspection necessary (SEE DTC C1741
AIR SUS RELAY CIRCUIT ).
NG: REPAIR CIRCUIT INDICATED BY OUTPUT CODE
OK:Go to next step
2.INSPECT HEIGHT CONTROL COMPRESSOR MOTOR
a. Disconnect the height control compressor motor connector.
b. Connect terminal 1 (B) to the battery positive (+) terminal, and terminal 2 (E) to the battery
negative (-) terminal.
c. Check the operating sound of the compressor motor.
OK:
Compressor motor operates.
HINT:
When a malfunction is found in the height control compressor motor, replace the height control
compressor assy.
NG: REPLACE HEIGHT CONTROL COMPRESSOR ASSY (SEE REPLACEMENT
)
OK:Go to next step

Fig. 95: Identifying Height Control Compressor Motor Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK:Go to next step
5.CHECK HARNESS AND CONNECTOR (HEIGHT CONTROL COMPRESSOR MOTOR - AIR
SUS RELAY) (SEE ELECTRONIC CIRCUIT INSPECTION PROCEDURE
)
a. Disconnect the AIR SUS relay from the fusible link block.
b. Measure the resistance according to the value (s) in the table below.
TESTER CONNECTION STANDARD SPECIFIED CONDITION
Tester ConnectionSpecified Condition
1 (B) - 2 (for AIR SUS relay)Below 1 ohms
1 (B) - Body ground10 Kohms or higher

Fig. 97: Identifying Air Sus Relay Location
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK:Go to next step
6.CHECK HARNESS AND CONNECTOR (AIR SUS RELAY - BODY GROUND) (SEE
ELECTRONIC CIRCUIT INSPECTION PROCEDURE
)
a. Measure the voltage according to the value (s) in the table below.
TESTER CONNECTION STANDARD SPECIFIED CONDITION
Tester ConnectionSpecified Condition
4 (for AIR SUS relay) - Body ground10 to 14 V

Fig. 98: Identifying Air Sus Relay Location
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK:Go to next step
7.INSPECT HEIGHT CONTROL SOLENOID VALVE
a. Connect the hand-held tester to the DLC3.
b. Turn the ignition switch to the ON position and turn the hand-held tester main switch on.
c. Select the item below in the ACTIVE TEST and operate it with the hand-held tester.
VEHICLE CONDITION / TEST DETAILS AIRSUS
ItemVehicle Condition / Test DetailsDiagnostic Note
FR SOLTurn OFF right front solenoid valve one second
after turning it ONOperation of solenoid (clicking sound)
can be heard
FL SOLTurn OFF left front solenoid valve one second
after turning it ONOperation of solenoid (clicking sound)
can be heard
RR SOLTurn OFF right rear solenoid valve one second
after turning it ONOperation of solenoid (clicking sound)
can be heard
RL SOLTurn OFF left rear solenoid valve one second Operation of solenoid (clicking sound)

10.INSPECT FOR CLOGGED AIR TUBE
a. Check the air tube visually for a clog or damage (see ON
-VEHICLE INSPECTION ).
OK:
Air tube is not clogged or damaged.
NG: REPAIR OR REPLACE AIR TUBE
OK: REPLACE SUSPENSION CONTROL ECU (SEE REPLACEMENT
)
CIRCUIT DESCRIPTION
The signal from the suspension control ECU operates the AIR SUS relay and the height control compressor
motor starts.
The height control compressor motor operates until the targeted vehicle height is reached. Then the height
control sensor sub-assy sends the signal to the suspension control ECU, and stops the height control compressor
motor.
Fig. 104: DTC C1751 And DTC C1752 Detecting Condition And Trouble Area

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.CHECK HEIGHT CONTROL COMPRESSOR CIRCUIT (SEE DTC C1742 HEIGHT
CONTROL COMPRESSOR CIRCUIT )
2.CHECK AIR LEAKAGE (SEE ON
-VEHICLE INSPECTION )
OK:
No leaks

Fig. 113: Identifying Suspension Control ECU Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: CHECK POWER SOURCE CIRCUIT (SEE DTC C1774 POWER SOURCE CIRCUIT
)
OK: REPLACE SUSPENSION CONTROL ECU (SEE REPLACEMENT
)
CIRCUIT DESCRIPTION
When the ignition switch is turned to the ON position, the D-IG1 relay is activated and battery voltage is
applied to terminal B of the suspension control ECU. When the ignition switch is turned off, the D-IG1 relay is
de-energized and the power source is cut off.
This power source energizes the suspension control actuator, height control solenoid valve, D-IG1 relay, each
IC and sensor.

HINT:
If the noise does not fall into any category in the table above, determine the cause using "Radio reception
problems" above. Refer to the multi-path and phasing sections.
HINT:
Before performing verification listed in the table below, check the fuse and relay.
Methods used to verify the cause of the problem are listed in order of probability in the verification
column.
AUDIO FUNCTION

Methods used to verify the cause of the problem are listed in order of probability in the verification
column.
Fig. 27: DTC Detecting Condition Chart (61 (Cassette))

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
2.TELEPHONE TRANSCEIVER AND SPEAKER RELAY (Physical address: 17D) [TEL]
a. Logical address: 01 (Communication control)
HINT:
Methods used to verify the cause of the problem are listed in order of probability in the verification
column.