sensor LEXUS LS430 2003 Factory Repair Manual

Fig. 64: Signal Waveform Graph
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: REPLACE CRUISE CONTROL ECU ASSY (SEE REPLACEMENT
)
CIRCUIT DESCRIPTION
The millimeter wave radar sensor and cruise control ECU (distance control ECU) transmit the data for general
vehicle control and diagnosis function along the communication line.
The cruise control ECU (distance control ECU) determines the presumed R information based on the signal
from the steering wheel and yaw rate sensor.
The cruise control ECU (distance control ECU) transmits the current vehicle speed and presumed R information
to the millimeter wave radar sensor.

Fig. 65: DTC U1102 Problem Symptom Diagnostic Chart
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WIRING DIAGRAM
Fig. 66: Wiring Diagram
- Lost Communication With Radar Sensor
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INSPECTION PROCEDURE
1.CHECK WIRE HARNESS AND CONNECTOR (DISTANCE CONTROL ECU - MILLIMETER
WAVE RADAR SENSOR)
a. Disconnect the distance control ECU and millimeter wave radar sensor connectors.
b. Measure the resistance according to the value(s) in the table below.
Standard:
DISTANCE CONTROL ECU AND MILLIMETER WAVE RADAR SENSOR TERMINALS
RESISTANCE SPECIFICATION
Tester connectionConditionSpecified value
D2-23 (LRRD) - M7-4 (LRRD)AlwaysBelow 1 ohms
D2-13 (IGB) - M7-5 (IGB)AlwaysBelow 1 ohms
D2-23 (LRRD) - Body groundAlways10 kohms or higher
D2-13 (IGB) - Body groundAlways10 kohms or higher

Fig. 68: Disconnecting Millimeter Wave Radar Sensor Connector
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR
OK: Go To Next Step.
2.INSPECT CRUISE CONTROL ECU ASSY (DISTANCE CONTROL ECU)
a. Reconnect the cruise control ECU (distance control ECU) connector.
b. Turn the ignition switch to the ON position.
c. Measure the voltage according to the value(s) in the table below.
Standard:

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Fig. 70: Signal Waveform Graph

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: REPLACE MILLIMETER WAVE RADAR SENSOR ASSY (SEE ADJUSTMENT
)
CIRCUIT DESCRIPTION
This DTC is output when the scanning angle of the millimeter wave radar sensor is incorrect.
This DTC is also output when the ECU detects that the millimeter wave radar sensor beam axis is in an
incorrect position.
Fig. 71: DTC P1572 Problem Symptom Diagnostic Chart

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HINT:
If the beam axis deviates to the distance 4.0 to 6.0 m, upper/lower side +/-2° or more and/or the right/left side
+/-4° or more, this DTC is detected.
INSPECTION PROCEDURE
1.ADJUST MILLIMETER WAVE RADAR SENSOR ASSY (SEE ADJUSTMENT
)
CIRCUIT DESCRIPTION
This circuit detects the angle and direction of steering and automatically transmits its signal to the skid control
ECU and distance control ECU.
Fig. 72: DTC U0126 Problem Symptom Diagnostic Chart

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INSPECTION PROCEDURE
HINT:
This circuit uses CAN for communication. Therefore, if there are any malfunctions in the communication
circuit, one or more DTCs in the CAN communication system is/are output.
1.GO TO CAN COMMUNICATION SYSTEM (SEE PRECAUTION
)
CIRCUIT DESCRIPTION
This circuit detects the yaw rate of the vehicle and transmits its signal to the skid control ECU and distance
control ECU.

Fig. 73: DTC U0123 Problem Symptom Diagnostic Chart
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
HINT:
This circuit uses CAN for communication. Therefore, if there are any malfunctions in the communication
circuit, one or more DTCs in the CAN communication system is/are output.
1.GO TO CAN COMMUNICATION SYSTEM (SEE PRECAUTION
)
CIRCUIT DESCRIPTION
<0037004b004c005600030046004c005500460058004c005700030053005500520059004c004700480056000300530052005a004800550003005700520003005200530048005500440057004800030057004b00480003004600550058004c00560048000300
4600520051005700550052004f00030028002600380003000b[distance control ECU).
The distance control ECU determines the vehicle that you are following based on data from the laser sensor and
then decides how much acceleration and/or deceleration is needed to maintain the set distance. It also requests
the skid control ECU to apply braking and sound the buzzer.
WIRING DIAGRAM

CIRCUIT DESCRIPTION
This circuit provides power to operate the millimeter wave radar sensor.
The millimeter wave radar sensor emits radar 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 an object in front. This data is transmitted to the cruise
control ECU (distance control ECU).
HINT:
The millimeter wave radar sensor monitors the radar emission and reception by itself. This DTC is detected
when it cannot monitor.
When rain drops or snowflakes strike the radar sensor face, the distance between the vehicle in front and your
own vehicle cannot be measured correctly.
The dynamic radar 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.
Emissions from the vehicle in front or from other lanes are heavy.
WIRING DIAGRAM

Fig. 76: Wiring Diagram - Sensor Power Source Circuit
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.INSPECT MILLIMETER WAVE RADAR SENSOR ASSY
a. Disconnect the millimeter wave radar sensor connector.
b. Measure the voltage according to the value(s) in the table below.
Standard:
MILLIMETER WAVE RADAR SENSOR TERMINALS VOLTAGE SPECIFICATION
NG: Go to step
Tester connectionConditionSpecified value
M7-5 (IGB) - Body groundIgnition SW ON10 to 14V

Fig. 77: Disconnecting Millimeter Wave Radar Sensor Connector
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: Go To Next Step.
2.CHECK WIRE HARNESS AND CONNECTOR
a. Disconnect the ECM E3 connector.
b. Measure the resistance according to the value(s) in the table below.
Standard:
MILLIMETER WAVE RADAR SENSOR TERMINALS RESISTANCE SPECIFICATION
Tester connectionConditionSpecified value
M7-1 (LGND) - E3-29 (LGND)AlwaysBelow 1 ohms

Fig. 78: Disconnecting Millimeter Wave Radar Sensor Connector
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
M7-1 (LGND) - Body groundAlways10 kohms or higher
M7-2(SGND) - Body groundAlwaysBelow 1 ohms