2003 LEXUS LS430 replacement

Fig. 65: Identifying Cruise Control ECU Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
d. Check the signal waveform between terminal LRRD (D2-23) of the cruise control ECU (distance
control ECU) and body ground.
OK:
A waveform similar to that in the illustration to the left is output.
HINT:
Gauge set: 2 V/DIV, 5 ms/DIV
Condition: Ignition switch ON
NG: REPLACE CRUISE CONTROL ECU ASSY (SEE REPLACEMENT
)

Fig. 66: Signal Waveform Graph
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: REPLACE LASER SENSOR (SEE REPLACEMENT
)
CIRCUIT DESCRIPTION
The laser sensor emits laser beams towards an object in front and measures the distance and direction of the
object by receiving the beam reflections. Based on the reflections, the sensor calculates the difference in speed
between your own vehicle and on object in front. This data is transmitted to the cruise control ECU (distance
control ECU).
DTC P1570 PROBLEM SYMPTOM DIAGNOSTIC
HINT:
DTC No.Detection ItemTrouble Area
P1570The ECM outputs this trouble code when it detects the communication
error signal (from the cruise control ECU (distance control ECU) to the
laser sensor) for 0.15 sec. or more while the dynamic laser cruise control
is in operation.laser sensor

The laser sensor monitors the laser emission and reception by itself. This DTC is detected when it cannot
monitor.
When rain drops or snowflakes strike the laser sensor face, the distance between the vehicle in front and your
own vehicle cannot be measured correctly.
The dynamic laser cruise control system functions by detecting the reflector of the vehicle directly in front. In
the following cases, the system may not be able to detect the vehicle in front and may not properly maintain the
correct vehicle-to-vehicle distance.
The vehicle in front is a tall trailer.
The back of the vehicle in front is extremely dirty.
Emissions from the vehicle in front or from other lanes are heavy.
The vehicle in front has no reflector.
The laser sensor is receiving a strong flash of light (sunlight, etc.).
INSPECTION PROCEDURE
1.ADJUST LASER SENSOR (SEE ADJUSTMENT
)
HINT:
It is necessary to make the ECM recognize spec information (whether the vehicle is equipped with the
dynamic laser or not). When this procedure has not been carried out, this DTC may be output.
1. Clear the DTC and then recheck for DTCs.
OK: DTC is not output.
HINT:
If DTC P1570 is still output after performing the above procedures, replace the laser sensor.
NG: REPLACE LASER SENSOR (SEE REPLACEMENT
)
OK: SYSTEM OK
CIRCUIT DESCRIPTION
This DTC is output when the scanning angle of the laser sensor is incorrect.
This DTC is also output when the laser sensor optical axis is in an incorrect position is detected.
DTC P1572 PROBLEM SYMPTOM DIAGNOSTIC

OK: When cruise control main switch operation is performed the standard values will be above.
Result:
RESULT DETAIL
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. 79: 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.
Standard:
CRUISE CONTROL MAIN SWITCH CONNECTOR TERMINALS RESISTANCE
SPECIFICATION
RES/ACC SWRES/ACC SW signal / ON or
OFFON: RES/ACC SW ON OFF:
RES/ACC OFF-
OKA
NG (All items are defective)B
NG (One to Four items are defective)C
Switch conditionTester connectionResistance(ohms)

NG: REPLACE CRUISE CONTROL MAIN SWITCH ASSY (SEE REPLACEMENT )
OK: Go To Next Step.
3.INSPECT SPIRAL CABLE SUB-ASSY
a. Disconnect the spiral cable sub-assy connector.
b. Measure the resistance according to the value(s) in the table below.
Standard:
SPIRAL CABLE SUB-ASSY CONNECTOR TERMINALS RESISTANCE SPECIFICATION
NeutralA-2 - A-3, A-3 - A-410 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
MODEA-3 - A-4Below 1 ohms
Terminal No.Specified value
A-2 - C13-2Below 1 ohms
A-3 - C13-3Below 1 ohms
A-4 - C13-4Below 1 ohms

Fig. 80: Identifying Spiral Cable Sub-Assy Connector
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPLACE SPIRAL CABLE SUB-ASSY (SEE REPLACEMENT
)

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: REPLACE ECM (SEE REPLACEMENT )
CIRCUIT DESCRIPTION
The distance control switch sets the vehicle-to-vehicle distance mode.
The distance control switch (DISP2 button) is installed in the steering pad switch modulator. The vehicle-to-
vehicle distance set value can be changed by operating the distance control switch (DISP2 button) while the
dynamic laser cruise control system is in operation.
The steering pad switch modulator uses BEAN to communicate with each ECU. Therefore it does not have a
direct connection with the ECM. If there are any malfunctions in the communication line of the steering pad
switch modulator, one or more DTCs in the multiplex communication system is/are output.
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. Select the item "DISP2 (MULTI MODE SW)" in the DATA LIST, and read its value on the hand-
held tester.
d. Check the indication displayed on the hand-held tester, when the steering pad switch (DISP2) is
ON and when it is OFF.
MULTI-INFORMATION DISPLAY CONTROL SWITCH (STEERING PAD SWITCH
MODULATOR):
DATA LIST (MULTI-INFORMATION DISPLAY CONTROL SWITCH (STEERING PAD
SWITCH MODULATOR))
OK: When switch operation is performed the standard values will be above.
NG: REPLACE STEERING PAD SWITCH MODULATOR (SEE REPLACEMENT
)
OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN DIAGNOSTIC TROUBLE
CODE CHART
Item
Measurement 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.-

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 "CCS INDICATOR M", "CCS INDICATOR S", "CCS READY M" or "CCS
READY S" in the DATA LIST, and read its value on the hand-held tester.
d. Check the CRUISE main indicator light and READY indicator light, when the cruise control main
switch is ON and when it is OFF.
CC (ECM):
DATA LIST (CC (ECM))
OK: When cruise control main switch operation is performed the standard values will be above.
HINT:
*1 is OK, but *2 is NG --> DTC output or ECM failure
NG: REPLACE ECM (SEE REPLACEMENT
)
OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS
TABLE
CIRCUIT DESCRIPTION
When the cruise control ECU (distance control ECU) detects that the wipers are operating, the dynamic laser
cruise control system will be cancelled.
HINT:
A wiper switch si
gnal is sent to the distance control ECU via CAN and BEAN. Therefore if there are any
ItemMeasurement Item / Display
(Range)Normal ConditionDiagnostic
Note
CCS READY MCruise control system standby
condition (Main CPU) / ON or OFFON <=> OFF: Change ON/OFF
each time Main SW is pushed.*1
CCS READY SCruise control system standby
condition (Sub CPU) / ON or OFFON <=> OFF: Change ON/OFF
each time Main SW is pushed.*1
CCS
INDICATOR MCruise indicator signal (Main CPU) /
ON or OFFON: "CCS READY" ON OFF:
"CCS READY" OFF*2
CCS
INDICATOR SCruise indicator signal (Sub CPU) /
ON or OFFON: "CCS READY" ON OFF:
"CCS READY" OFF*2