2003 LEXUS LS430 ignition

POWER SOURCE CIRCUIT ) is displayed, carry out the necessary inspection. If they are output at the
same time, carry out the necessary inspection for DTC C1774 first.
NG: REPAIR CIRCUIT INDICATED BY OUTPUT CODE
OK:Go to next step
2.PERFORM ACTIVE TEST BY HAND-HELD TESTER
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
d. Check the operation sound of the height control solenoid valve when the solenoid is turned on
through the ACTIVE TEST.
OK:
An operation sound is heard 1 second after the height control solenoid valve is turned on.
NG: Go to step 3
OK: REPLACE SUSPENSION CONTROL ECU (SEE REPLACEMENT
)
3.INSPECT HEIGHT CONTROL SOLENOID VALVE
HEIGHT CONTROL SOLENOID VALVE FRONT:
a. Disconnect the height control solenoid valve connector.
b. Measure the resistance according to the value (s) in the table below.
TESTER CONNECTION STANDARD SPECIFIED CONDITION STANDARD (RH)
TESTER CONNECTION STANDARD SPECIFIED CONDITION STANDARD (LH)
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
after turning it ONOperation of solenoid (clicking sound)
can be heard
Tester ConnectionSpecified Condition
2 (GND) - 3 (SLFR)10 to 14 ohms

POWER SOURCE CIRCUIT ) is displayed, carry out the necessary inspection. If they are output at the
same time, carry out the necessary inspection for DTC C1774 first.
NG: REPAIR CIRCUIT INDICATED BY OUTPUT CODE
OK:Go to next step
2.PERFORM ACTIVE TEST BY HAND-HELD TESTER
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
d. Check the operation sound of the AIR SUS relay when operating it with the hand-held tester.
OK:
The operation sound of the AIR SUS relay can be heard.
NG: Go to step 3
OK: REPLACE SUSPENSION CONTROL ECU (SEE REPLACEMENT
)
3.INSPECT AIR SUS RELAY
a. Remove 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
NG: REPLACE AIR SUS RELAY
OK:Go to next step
Item
Vehicle Condition / Test
Details
Diagnostic Note
MOTOR RELAYAIR SUS relay / ON or OFFOperation of solenoid (clicking sound) can
be heard
Tester ConnectionSpecified Condition
1 - 210 Kohms higher
1 - 2Below 1 ohms (When battery voltage is applied to terminals 3 and 4)

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)

NG: REPAIR OR REPLACE AIR TUBE
OK:Go to next step
3.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
d. Check the operation sound of the height control solenoid valve when the solenoid is turned on
through the ACTIVE TEST.
OK:
An operation sound is heard 1 second after the height control solenoid valve is turned on.
NG: Go to step 4
OK: Go to step 6
4.INSPECT HEIGHT CONTROL SOLENOID VALVE
HEIGHT CONTROL SOLENOID VALVE FRONT RH:
a. Disconnect the height control solenoid valve connector.
b. Connect terminal 3 (SLFR) to the battery positive (+) terminal, and terminal 2 (GND) to the battery
negative (-) terminal.
c. Check the operating sound of the height control solenoid valve.
OK:
It should make an operating sound (click).
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
after turning it ONOperation of solenoid (clicking sound)
can be heard

POWER SOURCE CIRCUIT ).
NG: REPAIR CIRCUIT INDICATED BY OUTPUT CODE
OK:Go to next step
2.CHECK HARNESS AND CONNECTOR (HEIGHT CONTROL SENSOR SUB-ASSY POWER
SOURCE) (SEE ELECTRONIC CIRCUIT INSPECTION PROCEDURE
)
a. Disconnect the height control sensor sub-assy connector.
b. Turn the ignition switch to the ON position.
c. Measure the voltage according to the value (s) in the table below.
TESTER CONNECTION STANDARD SPECIFIED CONDITION STANDARD (FRONT
RH)
TESTER CONNECTION STANDARD SPECIFIED CONDITION STANDARD (FRONT
LH):
TESTER CONNECTION STANDARD SPECIFIED CONDITION STANDARD (REAR RH)
TESTER CONNECTION STANDARD SPECIFIED CONDITION STANDARD (REAR LH)
NG: CHECK HEIGHT CONTROL SENSOR SUB-ASSY CIRCUIT (SEE DTC C1711 RIGHT
FRONT HEIGHT CONTROL SENSOR CIRCUIT, DTC C1712 LEFT FRONT HEIGHT
CONTROL SENSOR CIRCUIT,DTC C1713 RIGHT REAR HEIGHT CONTROL SENSOR
CIRCUIT, DTC C1714 LEFT REAR HEIGHT CONTROL SENSOR CIRCUIT )
Fig. 110: Identifying Front Height Control Sensor Sub
-Assy Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
Tester ConnectionSpecified Condition
H14-1 (SHB) - H14-4 (SHG)4.5 to 5.5 V
Tester ConnectionSpecified Condition
H13-1 (SHB) - H13-4 (SHG)4.5 to 5.5 V
Tester ConnectionSpecified Condition
H31-1 (SHB) - H31-3 (SHG)4.5 to 5.5 V
Tester ConnectionSpecified Condition
H30-1 (SHG) - H30-3 (SHB)4.5 to 5.5 V

Fig. 111: Identifying Rear Height Control Sensor Sub-Assy Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK:Go to next step
3.CHECK HARNESS AND CONNECTOR (SUSPENSION CONTROL ECU - BODY GROUND)
(SEE ELECTRONIC CIRCUIT INSPECTION PROCEDURE
)
a. Turn the ignition switch off.
b. Disconnect the suspension control ECU A21 connector.
c. Measure the resistance according to the value (s) in the table below.
TESTER CONNECTION STANDARD SPECIFIED CONDITION
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK:Go to next step
Tester ConnectionSpecified Condition
A21-23 (SBL3) - Body ground10 Kohms or higher

Fig. 112: Identifying Suspension Control ECU Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
4.INSPECT SUSPENSION CONTROL ECU (ECU POWER SOURCE)
a. Turn the ignition switch off.
b. Measure the voltage according to the value (s) in the table below.
TESTER CONNECTION STANDARD SPECIFIED CONDITION
Tester ConnectionSpecified Condition
A20-1 (B) - A20-4 (GND)10 to 14 V

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.