LEXUS LS430 2003 Factory Repair Manual

Fig. 62: 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 MILLIMETER WAVE RADAR SENSOR ASSY
a. Reconnect 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

c. Check the signal waveform between terminal LRDD (M7-3) of the millimeter wave radar sensor
and body ground.
OK:
A waveform similar to that in the illustration to the left is output.
HINT:
Gauge set: 1 V/DIV, 2 ms/DIV
Condition: Ignition switch ON
NG: REPLACE MILLIMETER WAVE RADAR SENSOR ASSY (SEE ADJUSTMENT
)
Fig. 63: Reconnecting Millimeter Wave Radar Sensor Connector

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
Tester connectionConditionSpecified value
M7-5 (IGB) - Body groundIgnition SW ON10 to 14V

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
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
WIRING DIAGRAM
Fig. 66: Wiring Diagram
- Lost Communication With Radar Sensor
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
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. 67: Disconnecting Distance Control ECU Connector
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

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:

CRUISE CONTROL ECU TERMINALS VOLTAGE SPECIFICATION
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. 69: Reconnecting Cruise Control ECU (Distance Control ECU) Connector

Tester connectionConditionSpecified value
D2-13 (IGB) - Body groundIgnition SW ON10 to 14V

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

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

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
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