2003 LEXUS LS430 cruise control

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-

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

This DTC indicates the internal abnormalities of the ECM.
DTC P0607 PROBLEM SYMPTOM DIAGNOSTIC
HINT:
The ECM receives signals from each sensor to control all the functions of the cruise control with the
microcomputer.
When a trouble code is detected, fail-safe remains on until the ignition switch is turned off.
INSPECTION PROCEDURE
1.REPLACE ECM (SEE REPLACEMENT
)
CIRCUIT DESCRIPTION
The cruise control main switch operates seven functions: SET, COAST, TAP-DOWN, RESUME, ACCEL,
TAP-UP, and CANCEL. The SET, TAP-DOWN and COAST functions, and the RESUME, TAP-UP and
ACCEL functions are operated with the same switch respectively. The cruise control main switch is an
automatic return type switch which turns on only while operating it in each arrow direction and turns off after
releasing it. The internal contact point of the cruise control main switch is turned on with the switch operation.
Then the ECM reads the resistance value that has been changed by the switch operation to control SET,
COAST, RESUME, ACCEL and CANCEL.
WIRING DIAGRAM
DTC No.Detection ItemTrouble Area
P0607The ECM has a supervisory CPU and a control ECU inside. When
each input STP signal is different for 0.15 sec. or more, this trouble
code is output. This trouble code is output after 0.4 sec. has passed
from the time the cruise cancel input signal (STP input) is input into
the ECM.ECM

Fig. 26: Wiring Diagram - Cruise Control Switch Circuit
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.
c. Accordin
g to the display on the tester, read the "DATA LIST".

Fig. 27: Identifying Cruise Control Main Switch Positions
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
HAND-HELD TESTER VALUE (ECM)
OK: When cruise control main switch operation is performed the standard values will be above.
RESULT DETAIL
Item
Measurement Item /
Display (Range)
Normal ConditionDiagnostic Note
MAIN SW (MAIN)Main SW signal (Main
CPU) / ON or OFFON: Main SW ON (Pushed on)
OFF Main SW OFF (Pushed off)-
MAIN SW (SUB)Main SW signal (Main
CPU) / ON or OFFON: Main SW ON (Pushed on)
OFF Main SW OFF (Pushed off)-
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 OFF-

B: Go to step 2
C: REPLACE CRUISE CONTROL MAIN SWITCH ASSY (SEE REPLACEMENT
)
A: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
2.INSPECT CRUISE CONTROL MAIN SWITCH ASSY
a. Disconnect the cruise control main switch connector.
Fig. 28: Checking Cruise Control Main Switch Assy

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
b. Measure the resistance according to the value(s) in the table below.
CRUISE CONTROL MAIN SWITCH CONNECTOR TERMINALS RESISTANCE
SPECIFICATION
NG: REPLACE CRUISE CONTROL MAIN SWITCH ASSY (SEE REPLACEMENT
)
OK: Go to next step
OKA
NG (All items are defective.)B
NG (One to Four items are defective.)C
Switch conditionTester connectionResistance(ohms)
NeutralA-2 - A-310 kohms or higher
RES/ACCA-2 - A-3210 to 270
SET/COASTA-2 - A-3560 to 700
CANCELA-2 - A-31,380 to 1,700
Main Switch OFFA-2 - A-310 kohms or higher
Main Switch ONA-2 - A-3Below 1 ohms

Fig. 31: [Disconnecting ECM Connector]
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: REPLACE ECM (SEE REPLACEMENT
)
CIRCUIT DESCRIPTION
The ECM detects a cruise control switch signal and sends it to the combination meter via CAN and
BEAN. Then the CRUISE main indicator light comes on.
The CRUISE main indicator light circuit uses CAN and BEAN for communication. If there are any
malfunctions in this circuit, check for DTCs in the CAN communication system and multiplex
communication system.
INSPECTION PROCEDURE
1.PERFORM ACTIVE TEST BY HAND-HELD TESTER
a. Connect the hand-held tester to the DLC3.
b. Check the CRUISE main indicator light by using ACTIVE TEST.
ACTIVE TEST DETAIL (COMBINATION METER ASSY)
OK: Indicator light comes on/goes off.
NG: GO TO COMBINATION METER SYSTEM (SEE HOW TO PROCEED WITH
TROUBLESHOOTING )
OK: Go to next step
2.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 the display on the hand-held tester.
DATA LIST (CC (ECM))
ItemVehicle Condition / Test DetailsDiagnostic Note
CRUISE INDIC"CRUISE" indicator is ON / OFF-
ItemMeasurement Item / Display
(Range)Normal ConditionDiagnostic
Note
CCS INDICATOR
MCruise indicator signal (Main
CPU) /ON or OFFON: "CCS READY" ON OFF:
"CCS READY" OFF-

OK: When cruise control main switch operation is performed the standard values will be above.
NG: REPLACE ECM (SEE REPLACEMENT
)
OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOMS
TABLE
CIRCUIT DESCRIPTION
Making a short circuit between terminals TC and CG of the DLC3 will output DTCs from the DLC3.
WIRING DIAGRAM
Fig. 32: [Wiring Diagram
- Diagnosis Circuit]
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
HINT:
When a particular warning light stays blinking, a ground short in the wiring of terminal TC of the DLC3 or an
internal ground short in the relevant ECU is suspected.
INSPECTION PROCEDURE
CCS
INDICATORSCruise indicator signal (Sub
CPU) /ON or OFFON: "CCS READY" ON OFF:
"CCS READY" OFF-