2003 LEXUS LS430 Ecm

Fig. 33: Connecting Hand-Held Tester To DLC3
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
1.Constant speed control mode and vehicle-to-vehicle distance control mode:
If the following conditions are detected while the dynamic laser cruise control is in operation, the system
clears the stored vehicle speed in the ECM and cancels the dynamic laser cruise control operation.
Fig. 34: Identifying CRUISE Main Indicator Light And Master Warning Light

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Fig. 35: Fail
-Safe Chart
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2.Only in the vehicle-to-vehicle distance control mode:
If the following conditions are detected while the dynamic laser cruise control is in operation, the system
clears the stored vehicle speed in the ECM and cancels the dynamic laser cruise control operation.
Fig. 36: Identifying CRUISE Main Indicator Light And Master Warning Light

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
Fig. 37: Fail
-Safe Chart
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
3.Only in the vehicle-to-vehicle distance control mode:
If the following conditions are detected while the dynamic laser cruise control is in operation, the system
maintains the stored vehicle speed in the ECM and cancels the d
ynamic laser cruise control operation.

Fig. 38: Identifying Master Warning Light
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Fig. 39: Fail
-Safe Chart (1 Of 2)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
4.Constant speed control mode and vehicle-to-vehicle distance control mode:
If the following conditions are detected while the dynamic laser cruise control is in operation, the system
clears the stored vehicle speed and cancels the dynamic laser cruise control operation.
HINT:
In the vehicle-to-vehicle distance control mode, the stored vehicle speed in the ECM is maintained.
Fig. 40: Fail
-Safe Chart (2 Of 2)

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1.DATA LIST
HINT:
From the DATA LIST displayed on the hand-held tester, the value of components such as the switch,
sensor, and actuator can be read without parts removal. Reading the DATA LIST as the first step of
troubleshooting is one way to shorten labor time.
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, read the "DATA LIST".
CC (ECM):
DATA LIST (CC (ECM))
Item
Measurement Item /
Display (Range)
Normal ConditionDiagnostic Note
ACCEL REQUESTAccelerator request signal /
min.: -2621.44 k/h/s, max.:
2621.36 k/h/sNo vehicle in front-
VEHICLE
DISTANCELaser sensor / min.: 0 m (0ft),
max.: 255m (836.65 ft)Distance to the vehicle in front-
L/C OPTION FLAGLaser cruise option flag / NO,
YESYES: Vehicle to vehicle distance
mode-
DISTANCE TIMECar distance time setting
condition /SHRT, MID,
LONG, NOThe vehicle selected by distance
control switch-
O/D CUT RQSTO/D cut request / NOT REQ,
REQUESTNOT REQ: Idling-
3RD SHIFT DOWNShift down request to 3rd
gear / NOT REQ, REQUESTNOT REQ: Idling-
4TH SHIFT DOWNShift down request to 4th
gear / NOT REQ, REQUESTNOT REQ: Idling-
ALARM RQSTAlarm request signal / NOT
REQ, REQUESTREQUEST: When beeping NOT
REQ: When not beeping-
THROTTLE CLOSEAll throttle close request /
NOT REQ, REQUESTON: REQUEST OFF: NOT
REQUEST-
BRAKE CTRL RQSTBrake control request / NOT
REQ, REQUESTON: REQUEST OFF: NOT
REQUEST-
TARG DECL SLOPECruise target deceleration
slope / 0.03, 0.06, 0.11, 0.160.03, 0.06, 0.11, 0.16-

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 main indicator light does not come on --> Indicator, W/H, or ECM failure
MULTI-INFORMATION DISPLAY CONTROL SWITCH (STEERING PAD SWITCH
MODULATOR):
DATA LIST (MULTI-INFORMATION DISPLAY CONTROL SWITCH (STEERING PAD
SWITCH MODULATOR))
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:
The ignition switch must be turned to the ON position to proceed to the ACTIVE TEST using the hand-
held tester.
COMBINATION METER ASSY:
ACTIVE TEST DETAIL (COMBINATION METER ASSY)
VSC FAIL SAFEVSC fail-safe flag/ON or
OFF--
ItemMeasurement Item / Display
(Range)Normal ConditionDiagnostic
Note
MULTI
DSP2 SWSteering pad switch (DISP2)
signal / ON or OFFON <=> OFF: Change ON/OFF each time
steering pad switch (DISP2) SW is pushed.-
ItemVehicle Condition / Test DetailsDiagnostic Note
CRUISE INDIC"CRUISE" indicator is ON / OFF-

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 the DTC chart below.
DIAGNOSTIC TROUBLE CODE CHART
L-CRUISE DISPGraphic area is ON / OFF((1))
L-CRS CHECK IND"CHECK CRUISE SYSTEM" indicator is ON / OFF-
L-CRS READY IND"RADAR READY" indicator is ON / OFF-
(1)The entire graphic area in the combination meter will light up.
DTCDescription
DTC P0500, DTC
P0503
VEHICLE SPEED SENSOR CIRCUIT MALFUNCTION
DTC P0571STOP LIGHT SWITCH CIRCUIT MALFUNCTION
DTC P0607INPUT SIGNAL CIRCUIT MALFUNCTION
DTC P1615, DTC
U1101
COMMUNICATION ERROR FROM DISTANCE CONTROL ECU TO
ECM
DTC P1616, DTC
U0100
COMMUNICATION ERROR FROM ECM TO DISTANCE CONTROL
ECU
DTC P1617DISTANCE CONTROL ECU MALFUNCTION
DTC P1630, DTC
U0122
COMMUNICATION ERROR FROM VSC TO ECM
DTC P1631, DTC
U0100
COMMUNICATION ERROR FROM ECM TO VSC
DTC P1575WARNING BUZZER MALFUNCTION
DTC P1578BRAKE SYSTEM MALFUNCTION
DTC U0235LOST COMMUNICATION WITH CRUISE CONTROL FRONT
DISTANCE RANGE SENSOR
DTC U1102LOST COMMUNICATION WITH RADAR SENSOR
DTC P1570RADAR SENSOR MALFUNCTION
DTC P1572IMPROPER AIMING OF RADAR SENSOR BEAM AXIS
DTC U0126LOST COMMUNICATION WITH STEERING ANGLE SENSOR MODULE
DTC U0123LOST COMMUNICATION WITH YAW RATE SENSOR MODULE

CIRCUIT DESCRIPTION
See CIRCUIT DESCRIPTION
.
Fig. 42: DTC P0500 And P0503 Problem Symptom Diagnostic Chart

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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.
The 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 ass
y, and the ECM turns the cruise control off.

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.
CC (ECM):
DATA LIST (CC (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.
Standard:
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