LEXUS LS430 2003 Factory Repair Manual

Fig. 74: Wiring Diagram - Distance Control ECU Power Source Circuit
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.INSPECT CRUISE CONTROL ECU ASSY (DISTANCE CONTROL ECU)
a. Disconnect the cruise control ECU (distance control ECU) connector.
b. Measure the voltage according to the value(s) in the table below.
Standard:
CRUISE CONTROL ECU TERMINALS VOLTAGE SPECIFICATION

c. Measure the resistance according to the value(s) in the table below.
Standard:
CRUISE CONTROL ECU TERMINALS RESISTANCE SPECIFICATION
NG: REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR
Fig. 75: Disconnecting Cruise Control ECU (Distance Control ECU) Connector

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS
TABLE
Tester connectionConditionSpecified value
D2-1 (+B) - Body groundIgnition SW ON10 to 14V
Tester connectionConditionSpecified Value
D2-10 (SGND) - Body groundAlwaysBelow 1 ohms
D2-12 (GND) - Body groundAlwaysBelow 1 ohms

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

Fig. 79: Disconnecting ECM E3 Connector
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR
OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS
TABLE
3.CHECK WIRE HARNESS AND CONNECTOR (MILLIMETER WAVE RADAR SENSOR -
DISTANCE CONTROL ECU)
a. Disconnect the cruise control ECU (distance control ECU) connector.
b. Measure the resistance according to the value(s) in the table below.
Standard:
MILLIMETER WAVE RADAR SENSOR AND DISTANCE CONTROL ECU TERMINALS
RESISTANCE
Tester connectionConditionSpecified value
D2-13 (IGB) - M7-5 (IGB)AlwaysBelow 1 ohms
D2-13 (IGB) - Body groundAlways10 kohms or higher

Fig. 80: Disconnecting Millimeter Wave Radar Sensor Connector
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

Fig. 81: Disconnecting Cruise Control ECU (Distance Control ECU) Connector
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR
OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS
TABLE
CIRCUIT DESCRIPTION
The cruise control main switch operates eight functions: SET, COAST, TAP-DOWN, RESUME, ACCEL,
TAP-UP, CANCEL and MODE. The SET, TAP-DOWN and COAST functions, and the RESUME, TAP-UP
and ACCEL functions are operated with the same switch. 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. The ECM then
reads the resistance value that has been changed by the switch operation to control MODE, SET, COAST,
RESUME, ACCEL and CANCEL.