LEXUS LS430 2003 Factory Repair Manual

HINT:
"3" is OK but "1" is NG --> ECM failure
"1" is OK but "2" is NG --> DTC output or ECM failure
"3" is OK but cruise indicator not turn on --> CRUISE MAIN indicator or wire harness or ECM failure
2.ACTIVE TEST
HINT:
Performing the ACTIVE TEST using the hand-held tester allows components such as the relay, VSV, and
actuator to operate without parts removal. Performing the ACTIVE TEST as the first step of
troubleshooting is one way to shorten labor time.
It is possible to display the DATA LIST during the ACTIVE TEST.
a. Connect the hand-held tester to the DLC3.
b. Turn the ignition switch to the ON position.
c. According to the display on the tester, perform the "ACTIVE TEST".
HINT:
CCS READY SCruise control system standby
condition (Sub CPU) / ON or
OFFON --> OFF: Change ON/OFF
each time Main SW is pushed in."1"
CCS INDICATOR
MCruise indicator signal (Main
CPU) /ON or OFFON: "CCS READY" ON OFF:
"CCS READY" OFF"2"
CCS
INDICATORSCruise indicator signal (Sub
CPU) /ON or OFFON: "CCS READY" ON OFF:
"CCS READY" OFF"2"
CANCEL SWCANCEL SW signal / ON or
OFFON: CANCEL SW ON OFF:
CANCEL SW OFF-
SET/COAST SWSET/COAST SW signal / ON or
OFFON: SET/COAST SW ON OFF:
SET/COAST SW OFF-
RES/ACC SWRES/ACC SW signal / ON or
OFFON: RES/ACC SW ON OFF:
RES/ACC SW OFF-
STP LIGHT SW MStop lamp SW signal (Main
CPU) / ON or OFFON: Brake pedal depressed OFF:
Brake pedal released-
STP LIGHT SW
S1Stop lamp SW signal (Sub
CPU) / ON or OFFON: Brake pedal depressed OFF:
Brake pedal released-
STP LIGHT SW
S2Stop light SW signal (Sub
CPU) / ON or OFFON: Brake pedal depressed OFF:
Brake pedal released-
SHIFT D POSPNP SW signal (D position) /
ON or OFFON: Shift D position OFF:
Except shift D position-

The ignition switch must be turned to the ON position to proceed ACTIVE TEST using the hand-held
tester.
ACTIVE TEST DETAIL (COMBINATION METER ASSY)
HINT:
If a trouble code is displayed during the DTC check, check the circuit listed for that code. For details of each
code, refer to chart.
DIAGNOSTIC TROUBLE CODE CHART
Fig. 17: Diagnostic Trouble Code Information Chart

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
CIRCUIT DESCRIPTION
See CIRCUIT DESCRIPTION
.
ItemVehicle Condition / Test DetailsDiagnostic Note
CRUISE INDIC"CRUISE" indicator is ON / OFF-
DTCDescription
DTC P0500 VEHICLE SPEED SENSOR CIRCUIT MALFUNCTION
DTC P0503 VEHICLE SPEED SENSOR CIRCUIT MALFUNCTION
DTC P0571 STOP LIGHT SWITCH CIRCUIT MALFUNCTION
DTC P0607 INPUT SIGNAL CIRCUIT MALFUNCTION

Fig. 18: DTC P0500 And P0503 Problem Symptom Diagnostic Chart
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
WIRING DIAGRAM
See WIRING DIAGRAM

INSPECTION PROCEDURE
See INSPECTION PROCEDURE
.
CIRCUIT DESCRIPTION
When the brake pedal is depressed, the stop lamp switch assy sends a signal to the ECM. When the ECM
receives this signal, it cancels the cruise control.
Fail-safe function operates to enable normal driving even if there is a malfunction in the stop lamp signal
circuit.
The cancel condition occurs when positive battery voltage is applied to terminal STP.
When the brake is applied, battery positive voltage is normally applied to terminal STP of the ECM through the
STOP fuse and the stop lamp switch assy, and the ECM turns the cruise control off.
Fig. 19: DTC P0571 Problem Symptom Diagnostic Chart

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

Fig. 20: Wiring Diagram - Stop Light Switch Circuit Malfunction
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.READ VALUE ON HAND-HELD TESTER
a. Connect the han
d-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 "STP LIGHT SW M", "STP LIGHT SW S1" or "STP LIGHT SW S2" in the DATA
LIST, and read its value displayed on the hand-held tester.
d. Check that the stop lamp comes on when the brake pedal is depressed, and goes off when the brake
pedal is released.
HAND-HELD TESTER VALUE (ECM)
OK: When brake pedal operation is performed the standard values will be above.
NG: Go to step 2
OK: REPLACE ECM (SEE REPLACEMENT
)
2.INSPECT STOP LAMP SWITCH ASSY
a. Disconnect the stop lamp switch assy connector.
b. Measure the resistance according to the value(s) in the table below.
STOP LAMP SWITCH TERMINALS RESISTANCE SPECIFICATION
NG: REPLACE STOP LAMP SWITCH ASSY
ItemMeasurement Item / Display
(Range)Normal ConditionDiagnostic
Note
STP LIGHT
SW MStop lamp SW signal (Main
CPU) / ON or OFFON: Brake pedal depressed OFF:
Brake pedal released-
STP LIGHT
SW S1Stop lamp SW signal (Sub CPU) /
ON or OFFON: Brake pedal depressed OFF:
Brake pedal released-
STP LIGHT
SW S2Stop lamp SW signal (Sub CPU) /
ON or OFFON: Brake pedal depressed OFF:
Brake pedal released-
Switch conditionTester connectionSpecified value
Switch pin free1 - 2Below 1 ohms
Switch pin free3 - 410 kohms or higher
Switch pin pushed in1 - 210 kohms or higher
Switch pin pushed in3 - 4Below 1 ohms

Fig. 21: Identifying Stop Lamp Switch Assy Connector
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: Go to next step
3.CHECK HARNESS AND CONNECTOR (STOP LAMP SWITCH - BATTERY)
a. Measure the voltage according to the value(s) in the table below.
STOP LAMP SWITCH TERMINALS VOLTAGE SPECIFICATION
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
Tester connectionConditionSpecified condition
S19-2 - Body groundAlways10 to 14 V
S19-3 - Body groundIgnition SW ON10 to 14 V

Fig. 22: Identifying Stop Lamp Switch Connector
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: Go to next step
4.INSPECT ECM
a. Reconnect the stop lamp switch connector.
b. Disconnect the E2 and E3 connectors from the ECM.
c. Turn the ignition switch to the ON position.
d. Measure the voltage according to the value(s) in the table below.
ECM CONNECTOR TERMINALS VOLTAGE RESISTANCE SPECIFICATION
RESULT DETAIL
Pedal conditionTester connectionSpecification
DepressedE2-4 (STP) - Body ground10 to 14 V
ReleasedE2-4 (STP) - Body groundBelow 1 V
DepressedE3-8 (ST1-) - Body groundBelow 1 V
ReleasedE3-8 (ST1-) - Body ground10 to 14 V

B: Go to step 5
C: REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LAMP SWITCH - ECM)
OKA
NG (STP terminal is NG)B
NG (ST1- terminals is NG)C

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Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
A: REPLACE ECM (SEE REPLACEMENT
)
5.INSPECT DRIVER SIDE J/B
a. Measure the voltage according to the value(s) in the table below.
Fig. 24: Identifying Driver Side Junction Block ECU Connectors

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
DRIVER SIDE JUNCTION BLOCK ECU TERMINALS VOLTAGE SPECIFICATION
NG: Go to step 6
OK: REPAIR OR REPLACE HARNESS OR CONNECTOR (DRIVER SIDE J/B ECU - ECM)
6.INSPECT DRIVER SIDE J/B
Pedal conditionTester connectionSpecification
DepressedD3-12 (STPO) - Body ground10 to 14 V
ReleasedD3-12 (STPO) - Body groundBelow 1 V