2003 LEXUS LS430 replacement

c. Check the operating sound of the exhaust solenoid valve.
OK:
It should make an operating sound (click).
HINT:
When a malfunction is found in the exhaust solenoid valve, replace the height control compressor assy.
NG: REPLACE HEIGHT CONTROL COMPRESSOR ASSY (SEE REPLACEMENT
)
OK:Go to next step
6.INSPECT HEIGHT CONTROL SENSOR LINK SUB-ASSY
a. Inspect and adjust the height control sensor link sub-assy (see ON
-VEHICLE INSPECTION ).
NG: REPLACE HEIGHT CONTROL SENSOR LINK SUB-ASSY
OK: CHECK AND REPAIR OR REPLACE PARTS
Air tube is clogged (see ON-VEHICLE INSPECTION ).
Compressor is faulty (see REPLACEMENT ).
Height control sensor sub-assy is faulty (see REPLACEMENT - HEIGHT CONTROL
SENSOR SUB-ASSY FRONT , REPLACEMENT - HEIGHT CONTROL SENSOR SUB-
ASSY REAR LH ).
Foreign material in the height control solenoid valve and/or exhaust solenoid valve (see
REPLACEMENT
- HEIGHT CONTROL COMPRESSOR ASSY , REPLACEMENT -
HEIGHT CONTROL VALVE SUB
-ASSY NO.1 , REPLACEMENT - HEIGHT CONTROL
VALVE SUB-ASSY NO.2 ).
Suspension control ECU malfunction (see REPLACEMENT ).
CIRCUIT DESCRIPTION

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.

Fig. 118: Tester Connection Specified Condition Description Table
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: REPLACE SUSPENSION CONTROL ECU (SEE REPLACEMENT
)
5.INSPECT SUSPENSION CONTROL ECU
a. Remove the suspension control ECU with connectors connected.
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
NG: Go to step 6
Tester ConnectionSpecified Condition
A20-1 (B) - A20-4 (GND)10 to 14 V

Fig. 119: Identifying Suspension Control ECU Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: REPLACE SUSPENSION CONTROL ECU (SEE REPLACEMENT
)
6.CHECK HARNESS AND CONNECTOR (SUSPENSION CONTROL ECU - BODY GROUND)
(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
A20-4 (GND) - Body groundBelow 1 ohms

Fig. 120: Identifying Suspension Control ECU 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
)
CIRCUIT DESCRIPTION
The speed sensors monitors the speed of the wheels, and sends an appropriate speed signals to the suspension
control ECU through the brake actuator assy (skid control ECU).
If trouble occurs in either the right rear speed sensor or left rear speed sensor, DTC (C1776) is output.

HINT:
There is tolerance of +/- 10 % in the speedometer indication.
NG: Go to step 2
OK: REPLACE SUSPENSION CONTROL ECU (SEE REPLACEMENT
)
2.CHECK DIAGNOSTIC CODE OUTPUT
a. Check if the normal system code is output in the VSC system (SEE DTC CHECK/CLEAR
).
OK:
No DTC is output in the VSC system.
NG: REPAIR CIRCUIT INDICATED BY OUTPUT CODE
OK:Go to next step
3.CHECK DIAGNOSTIC CODE OUTPUT
a. Check if the normal system code is output in the CAN communication system (SEE HOW TO
PROCEED WITH TROUBLESHOOTING ).
OK:
No DTC is output in the CAN communication system.
NG: REPAIR CIRCUIT INDICATED BY OUTPUT CODE
OK: REPLACE SUSPENSION CONTROL ECU (SEE REPLACEMENT
)
CIRCUIT DESCRIPTION
The steering angle sensor signal is sent to the suspension control ECU through the CAN communication
system. When there is a communication malfunction, it will be detected by the diagnosis function.
Fig. 123: DTC C1777 Detecting Condition And Trouble Area

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

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 DATA LIST and read its value displayed on the hand-held tester.
AIR SUS:
Fig. 125: Data List Value Description

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
d. Check that the steering wheel turning angle value of the steering angle position sensor displayed on
the hand-held tester changes when turning the steering wheel.
Standard:
Steering wheel turning angle value changes.
NG: Go to step 2
OK: REPLACE SUSPENSION CONTROL ECU (SEE REPLACEMENT
)
2.CHECK DIAGNOSTIC CODE OUTPUT
a. Check if the normal system code is output in the CAN communication system (SEE
SUSPENSION CONTROL ECU COMMUNICATION STOP MODE
).
OK:
No DTC is output in the CAN communication system.
NG: REPAIR CIRCUIT INDICATED BY OUTPUT CODE
OK:Go to next step
3.CHECK HARNESS AND CONNECTOR (STEERING SENSOR POWER SOURCE)
a. Disconnect the steering sensor S16 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
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
Tester ConnectionSpecified Condition
S16-1 (IG1) - S16-2 (ESS)10 to 14 V
S16-3 (BAT) - S16-2 (ESS)10 to 14 V

Fig. 126: Identifying Steering Sensor S16 Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: REPLACE STEERING SENSOR (SEE REPLACEMENT
)
CIRCUIT DESCRIPTION
The height control switch turns on when it is pressed to the "HIGH" side and turns off when pressed to the
"NORM" side. The ECU detects the height control switch condition and raises or lowers the vehicle height
accordingly.
B
y controlling the height control switch, the vehicle height can be set 30 mm (1.18 in.) higher in "HIGH" mode.