LEXUS LS430 2003 Factory Repair Manual

Fig. 127: DTC C1786 Detecting Condition And Trouble Area
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
HINT:
DTC C1786 is output only in the test mode.
WIRING DIAGRAM
Fig. 128: Height Control Switch Wiring Diagram

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.READ VALUE ON 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 DATA LIST and read its value displayed on the hand-held tester.
AIRSUS:

Fig. 129: Data List Value - Air sus
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
d. Check that the value displayed on the hand-held tester changes by pressing the height control
switch "HIGH" or "NORM" button.
OK:
Height control switch value changes.
NG: Go to step 2
OK: REPLACE SUSPENSION CONTROL ECU (SEE REPLACEMENT
)
2.INSPECT HEIGHT CONTROL SWITCH
a. Disconnect the height control switch connector.
b. Measure the resistance according to the value (s) in the table below.
TESTER CONNECTION STANDARD SPECIFIED CONDITION
NG: REPLACE HEIGHT CONTROL SWITCH
OK:Go to next step
Switch ConditionTester ConnectionSpecified Condition
"HIGH"2 (IGH) - 4 (HSW)Below 1 ohms
"NORM"2 (IGH) - 4 (HSW)10 Kohms or higher

Fig. 130: Identifying Height Control Switch Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
3.CHECK HARNESS AND CONNECTOR (SUSPENSION CONTROL ECU - HEIGHT
CONTROL SWITCH) (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
A20-15 (HSW) - H21-4 (HSW)Below 1 ohms
A20-15 (HSW) - Body ground10 Kohms or higher

Fig. 131: Identifying Suspension Control ECU Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

Fig. 132: Identifying Height Control Switch 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 (HEIGHT CONTROL SWITCH - 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
H21-2 (IGN) - Body groundBelow 1 ohms

Fig. 133: Identifying Height Control Switch 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 absorber control switch is used to select the attenuation modes of the shock absorber. 2 levels of
attenuation, "SPORT" and "NORM", are available.

Fig. 134: DTC C1787 Detecting Condition And Trouble Area
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
HINT:
DTC C1787 is output only in the test mode.
WIRING DIAGRAM
Fig. 135: Absorber Control Switch Wiring Diagram

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.INSPECT ABSORBER CONTROL SWITCH
a. Disconnect the absorber control switch connector.
b. Measure the resistance according to the value (s) in the table below.
TESTER CONNECTION STANDARD SPECIFIED CONDITION
Switch ConditionTester ConnectionSpecified Condition
"SPORT"2 (GND) - 4 (ECU1)Below 1 ohms
"NORM"2 (GND) - 4 (ECU1)10 Kohms or higher

Fig. 136: Identifying Absorber Control Switch Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPLACE ABSORBER CONTROL SWITCH
OK:Go to next step
2.CHECK HARNESS AND CONNECTOR (SUSPENSION CONTROL ECU - ABSORBER
CONTROL SWITCH) (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
A20-9 (SW1) - A18-4 (ECU1)Below 1 ohms
A20-9 (SW1) - Body ground10 Kohms or higher

Fig. 137: Identifying Suspension Control ECU Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

Fig. 138: Identifying Absorber Control Switch Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK:Go to next step
3.CHECK HARNESS AND CONNECTOR (ABSORBER CONTROL SWITCH - 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
A18-2 (GND) - Body groundBelow 1 ohms