LEXUS LS430 2003 Factory Repair Manual

Fig. 70: Identifying Exhaust Solenoid Valve Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
3.CHECK HARNESS AND CONNECTOR (SUSPENSION CONTROL ECU - EXHAUST
SOLENOID VALVE) (SEE ELECTRONIC CIRCUIT INSPECTION PROCEDURE
)
a. Disconnect the suspension control ECU A20 connector.
b. Measure the resistance according to the value (s) in the table below.
TESTER CONNECTION STANDARD SPECIFIED CONDITION
Tester ConnectionSpecified Condition
A20-5 (SLEX) - H12-1 (SLEX)Below 1 ohms
A20-5 (SLEX) - Body ground10 Kohms or higher

Fig. 71: Identifying Suspension Control ECU Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

Fig. 72: Identifying Exhaust Solenoid Valve Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK:Go to next step
4.CHECK HARNESS AND CONNECTOR (EXHAUST SOLENOID VALVE - BODY GROUND)
(SEE ELECTRONIC CIRCUIT INSPECTION PROCEDURE
)
a. Measure the resistance according to the value (s) in the table below.
TESTER CONNECTION STANDARD SPECIFIED CONDITION
Tester ConnectionSpecified Condition

Fig. 73: Identifying Exhaust Solenoid Valve Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: REPLACE SUSPENSION CONTROL ECU (SEE REPLACEMENT
)
H12-2 (GND) - Body groundBelow 1 ohms

CIRCUIT DESCRIPTION
FRONT HEIGHT CONTROL SOLENOID VALVE:
The height control valve sub-assy No. 1 (front height control solenoid valve) independently opens and closes
paths to the pneumatic cylinder for the front wheel side by receiving signals from the suspension control ECU.
HINT:
The right left solenoid valves are integrated and mounted on front side.
REAR HEIGHT CONTROL SOLENOID VALVE:
The height control valve sub-assy No. 2 (rear height control solenoid valve) independently opens and closes
paths to the pneumatic cylinder for the rear wheel side by receiving signals from the suspension control ECU.
HINT:
The right left solenoid valves are integrated and mounted on rear side.
Fig. 74: DTC C1737 And DTC C1740 Detecting Condition And Trouble Area

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

Fig. 75: Front Height Control Solenoid Valve Wiring Diagram
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
HINT:
Proceed to troubleshooting following the flow chart, regardless of whether or not DTC C1737, C1738, C1739
or C1740 is displayed.
1.RECONFIRM DTC
a. Check DTCs (SEE DTC CHECK/CLEAR
).
1. Confirm if DTC C1761 and/or C1774 is recorded.
OK:
DTC C1761 and/or C1774 is output.
HINT:
If either DTC C1761 (ECU malfunction) (SEE DTC C1761 ECU MALFUNCTION
or DTC C1774

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

Fig. 76: Identifying Height Control Solenoid Valve Front RH Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
c. RH:
Connect terminal 3 (SLFR) to the battery positive (+) terminal, and terminal 2 (GND) to the battery
negative (-) terminal.
d. LH:
Connect terminal 1 (SLFL) to the battery positive (+) terminal, and terminal 2 (GND) to the battery
negative (-) terminal.
e. Check the operating sound of the height control solenoid valve.
Tester ConnectionSpecified Condition
1 (SLFL) - 2 (GND)10 to 14 ohms

Fig. 77: Identifying Height Control Solenoid Valve Front LH Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK:
It should make an operating sound (click).
RESULT DESCRIPTION
HINT:
When a malfunction is found in the front solenoid valve, replace the height control valve sub-assy No. 1.
HEIGHT CONTROL SOLENOID VALVE REAR:
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)
OKA
NGB
Tester ConnectionSpecified Condition

TESTER CONNECTION STANDARD SPECIFIED CONDITION STANDARD (LH)
Fig. 78: Identifying Height Control Solenoid Valve Rear RH Connector Terminals

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
c. RH:
Connect terminal 1 (SLRR) to the battery positive (+) terminal, and terminal 2 (GND) to the battery
negative (-) terminal.
d. LH:
Connect terminal 3 (SLRL) to the battery positive (+) terminal, and terminal 2 (GND) to the battery
negative (-) terminal.
e. Check the operatin
g sound of the height control solenoid valve.
1 (SLRR) - 2 (GND)10 to 14 ohms
Tester ConnectionSpecified Condition
2 (GND) - 3 (SLRL)10 to 14 ohms