2003 LEXUS LS430 Identifying ac

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.

Fig. 116: Identifying AM1 Fuse Location
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: CHECK FOR SHORT IN ALL HARNESS AND CONNECTOR CONNECTED TO FUSE
AND REPLACE FUSE
OK:Go to next step
4.INSPECT FUSE (AIR SUS)
a. Remove the AIRSUS fuse from the driver side J/B.
b. Check fuse.
1. Check continuity of the AIRSUS fuse.
Standard:
Continuity

Fig. 117: Identifying Air sus Fuse Location
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: CHECK FOR SHORT IN ALL HARNESS AND CONNECTOR CONNECTED TO FUSE
AND REPLACE FUSE

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.

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.