LEXUS LS430 2003 Factory Repair Manual

Fig. 5: ECU Input And Output Signals Chart (2 Of 2)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

1.GENERAL
a. The dynamic radar cruise control system has two cruise control modes: the constant speed control
mode and vehicle-to-vehicle distance control mode.
The vehicle-to-vehicle distance control mode is always selected when starting up the
dynamic radar cruise control system.
Operation of the constant speed control mode is the same as that for the conventional type
cruise control system.
b. This system maintains the vehicle running at the speed that the driver has set, as long as there are
no vehicles ahead in the same lane. Then, the system maintains the vehicle distance that has been
set by the driver.
If the system detects a vehicle moving at a slower speed ahead while the driver is driving at a
constant speed, it closes the throttle valve to decelerate. If further deceleration is required, the
system controls the brake actuator in order to apply the brakes. Thereafter, if there are no vehicles
ahead within the set vehicle-to-vehicle distance because either the vehicle ahead or the driver has
changed lanes, the system accelerates slowly to reach the set vehicle speed and resumes driving at
the constant speed.
c. The constant speed control mode is designed to maintain a constant cruising speed. The vehicle-to-
vehicle distance control mode is designed to control cruising at a constant speed function,
deceleration cruising function, follow-up cruising function and acceleration cruising function.
d. The millimeter wave radar sensor and the distance control ECU (cruise control ECU) control the
system while the vehicle-to-vehicle distance control mode is in operation, and send signals to each
actuator and ECU.
e. In vehicle-to-vehicle distance control mode, the dynamic radar cruise control system receives
signals from the yaw rate & deceleration sensor and the steering angle sensor. Based on these
signals, it then estimates curve radius and compensates for information on the preceding vehicle
while turning. It can also compensate for the brake control when approaching another vehicle.
f. This system judges the existence of a vehicle in front and the distance to it based on the signals
from the radar sensor while the vehicle-to-vehicle distance control mode is in operation. Using this
information, the system informs the driver of any danger with the warning buzzer, performs brake
control, and turns on the stop lamp when approaching the vehicle in front.
g. The following illustration shows a control example under the following conditions: own vehicle
speed is 100 km/h (62 mph) and the speed of the vehicle in front is 80 km/h (50 mph).

Fig. 6: Dynamic Radar Cruise Control System Cruise Control Example Chart
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
Setting of the vehicle distance can be changed to 3 distances by operating the distance control
switch (DISP2 button): long (approximately 75 m (246 ft)), middle (approximately 50 m (164 ft)),
and short (approximately 30 m (98 ft)) when vehicle speed is approximately 90 km/h (55 mph).
HINT:
Vehicle distance increases and decreases in accordance with vehicle speed.
Controlling condition is indicated on the multi-information display in the combination meter.
2.FUNCTION OF MAIN COMPONENTS

Fig. 7: Main Components Function Chart (1 Of 2)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

Fig. 8: Main Components Function Chart (2 Of 2)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
3.LIMIT CONTROL
a. Low speed limit
The lowest possible limit of the speed setting range is set at approximately 45 km/h (28
mph). The cruise control system cannot be set when the driving vehicle speed is below the
low speed limit. Cruise control operation will be automatically canceled and the stored
vehicle speed will be erased when the vehicle speed goes below the low speed limit (40 km/h
(25 mph)) while the cruise control is in operation.
b. High speed limit (Constant speed control mode)
The highest possible limit of the speed setting range is set at approximately 200 km/h (125
mph). The cruise control system cannot be set when the driving vehicle speed is over the
high speed limit. Speed up using RESUME/ACCEL with the cruise control main switch assy
also cannot be set beyond the high speed limit.
c. Upper speed limit (Vehicle-to-vehicle distance control mode)
The set vehicle speed can be increased up to approximately 85 mph in USA and 135 km/h in
Canada.
4.CRUISE CONTROL OPERATION
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 assy is an automatic return type switch which turns on only while operating it in each arrow
direction and turns off after releasing it.
The dynamic radar cruise control system has two cruise control modes: the constant speed control mode
and vehicle-to-vehicle distance control mode.
The vehicle-to-vehicle distance control mode is always selected when starting up the dynamic radar
cruise control system.
Operation of the constant speed control mode is the same as that for the conventional type cruise
control system.
a. MODE CONTROL
Pushing the switch to MODE for more than 1 second while driving with the cruise control
main switch ON-OFF button on (RADAR READY is on) switches the mode to the constant
speed control mode.
b. SET CONTROL (Constant speed control mode)
Vehicle speed is stored and constant speed control is maintained when pushing the switch to
SET/ COAST while driving with the vehicle speed within the set speed range (between the
low and high speed limits) after pushing the cruise control main switch ON-OFF button on
(RADAR READY is on), and entering the constant speed control mode.
c. SET CONTROL (Vehicle-to-vehicle distance control mode)
Vehicle speed is stored and vehicle-to-vehicle control is maintained when pushing the switch
to SET/ COAST while driving with the cruise control main switch ON-OFF button on
(RADAR READY is on), and vehicle speed is within the set speed range (between the low
and high speed limits).
d. COAST CONTROL (Constant speed control mode)
The ECM makes the cruise control demanding throttle opening angle zero degrees and
decelerates the vehicle (the throttle valve is not fully closed due to the idle speed control,
etc.) when SET/COAST on the cruise control main switch is pressed and held while the
constant speed control mode is in operation. Vehicle speed, when the cruise control main
switch is released from SET/COAST, is stored and constant speed control is maintained.
e. COAST CONTROL (Vehicle-to-vehicle distance control mode)
When SET/COAST on the cruise control main switch is pressed and held while the vehicle-
to-vehicle distance control mode is in operation, the stored vehicle speed decreases by
approximately 5 km/h (CANADA) or 5 mph (USA) per second.
f. TAP-DOWN CONTROL (Constant speed control mode)
When tapping down on the cruise control main switch to SET/COAST (for approximately
0.5 second) while the constant speed control mode is in operation, the stored vehicle speed
decreases each time by approximately 1.6 km/h (1 mph). However, when the difference
between the driving and the stored vehicle speeds is more than 5 km/h (3 mph), the vehicle
speed, when the cruise control main switch is released from SET/COAST, will be stored and
constant speed control is maintained.
g. TAP-DOWN CONTROL (Vehicle-to-vehicle distance control mode)
When tappin
g down on the cruise control main switch to SET/COAST (for approximately

0.5 second) while the vehicle-to-vehicle distance control mode is in operation, the stored
vehicle speed decreases each time by approximately 5 km/h (CANADA) or 5 mph (USA).
h. ACCELERATOR CONTROL (Constant speed control mode)
The throttle valve motor of the throttle position sensor and motor is instructed by the ECM to
open the valve when RESUME/ACCEL on the cruise control main switch is pressed and held
while the constant speed control mode is in operation. Vehicle speed, when the cruise control
main switch is released from RESUME/ACCEL, is stored and constant speed control is
maintained.
i. ACCELERATION CONTROL (Vehicle-to-vehicle distance control mode)
When RESUME/ACCEL on the cruise control main switch is pressed and held while the
vehicle-to-vehicle distance control mode is in operation, the stored vehicle speed increases
by approximately 5 km/h (CANADA) or 5 mph (USA) per second.
Pushing the cruise control main switch to RESUME/ACCEL while following the vehicle in front
with the vehicle-to-vehicle distance control mode does not increase the actual vehicle speed, but
changes only the set vehicle speed.
j. TAP-UP CONTROL (Constant speed control mode)
When tapping up on the cruise control main switch to RESUME/ACCEL (for approximately
0.5 second) while the constant speed control mode is in operation, the stored vehicle speed
increases each time by approximately 1.6 km/h (1 mph). However, when the difference
between the driving and the stored vehicle speeds is more than 5 km/h (3 mph), the stored
vehicle speed will not be changed.
k. TAP-UP CONTROL (Vehicle-to-vehicle distance control mode)
When tapping up on the cruise control main switch to RESUME/ACCEL (for approximately
0.5 second) while the vehicle-to-vehicle distance control mode is in operation, the stored
vehicle speed increases each time by approximately 5 km/h (CANADA) or 5 mph (USA).
l. MANUAL CANCEL CONTROL
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550052004f00030056005c00560057004800500003005a004b[ile in operation. (The stored
vehicle speed in the ECM is maintained.)
Depressing the brake pedal
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57004b000f000300180057004b000f00030044005100470003[4th gears)
Pushing the cruise control main switch to CANCEL
Pushing the cruise control main switch ON-OFF button off (The stored vehicle speed
in the ECM is not maintained.)
m. RESUME CONTROL
If the cruise control operation was cancelled with the stop lamp switch or the CANCEL
switch, and if driving speed is within the limit range, pushing the cruise control main switch
to RESUME/ACCEL restores vehicle speed memorized at the time of cancellation, and
maintains constant speed control. In constant speed mode, once vehicle speed goes below the
low speed limit, RESUME operation is not possible even if accelerating up to the low speed
limit, or more, again.
5.BRAKE CONTROL

The distance control ECU (cruise control ECU) determines the distance between a vehicle in front and
your own, relative speed, target decreasing speed and deceleration rate to transmit a brake demand signal
to the skid control ECU via ECM.
6.DOWNSHIFT CONTROL
While the cruise control system is in operation, the gear may downshift from overdrive (6th) to 5th on an
uphill road. After the gear is shifted down to 5th, if the system determines that the uphill inclination has
become smaller based on throttle opening, the gear automatically returns to overdrive (6th).
7.AUTO CANCEL (FAIL-SAFE)
This system has an automatic cancellation function (fail-safe) (for details, SEE FAIL
-SAFE CHART ).
The hand-held tester can be used at steps 4, a, 6, 7, and 12.
1.VEHICLE BROUGHT TO WORK SHOP
Go to Next Step.
2.(SEE CUSTOMER PROBLEM ANALYSIS CHECK
)
Go to Next Step.
3.PROBLEM SYMPTOM CONFIRMATION
Go to Next Step.
4.CHECK BODY MULTIPLEX COMMUNICATION SYSTEM (SEE HOW TO PROCEED WITH
TROUBLESHOOTING )
a. Check if any DTCs are output.
HINT:
The ECM and cruise control ECU (distance control ECU) of this system are connected to the
multiplex communication system. Therefore, before starting troubleshooting, make sure to check
that there is no trouble in the multiplex communication system.
MULTIPLEX SYSTEM DTC IS OUTPUT (PROCEED TO "MULTIPLEX COMMUNICATION
SYSTEM ")
NO MULTIPLEX SYSTEM DTC (GO TO STEP 5)
5.CHECK CAN COMMUNICATION SYSTEM (SEE PRECAUTION
)

a. Check if any DTCs are output.
HINT:
The ECM and cruise control ECU (distance control ECU) of this system are connected to the CAN
communication system. Therefore, before starting troubleshooting, make sure to check that there is
no trouble in the CAN communication system.
CAN SYSTEM DTC IS OUTPUT (PROCEED TO "CAN COMMUNICATION SYSTEM
")
NO CAN SYSTEM DTC (GO TO STEP 6)
6.DTC CHECK AND CLEAR (SEE DTC CHECK/CLEAR
)
Go to Next Step.
7.DTC CHECK (OTHER THAN MULTIPLEX AND CAN SYSTEM DTC) (SEE DTC
CHECK/CLEAR )
TROUBLE CODE (GO TO STEP 8)
NORMAL SYSTEM CODE (GO TO STEP 9)
8.(SEE DIAGNOSTIC TROUBLE CODE CHART
)
GO TO STEP 12
9.PROBLEM SYMPTOM SIMULATION
SYMPTOM DOES NOT OCCUR (GO TO STEP 10)
SYMPTOM OCCURS (GO TO STEP 11)
10.SYMPTOM SIMULATION (SEE ELECTRONIC CIRCUIT INSPECTION PROCEDURE
)
Go to Next Step.
11.(SEE PROBLEM SYMPTOMS TABLE
)
Go to Next Step.
12.CIRCUIT INSPECTION (SEE DTC P0500 VEHICLE SPEED SENSOR CIRCUIT
MALFUNCTION, DTC P0503 VEHICLE SPEED SENSOR CIRCUIT MALFUNCTION -
DIAGNOSIS CIRCUIT
)
Go to Next Step.

13.(SEE TERMINALS OF ECU )
Go to Next Step.
14.PROBLEM IDENTIFICATION
Go to Next Step.
15.REPAIR OR REPLACE
Go to Next Step.
16.CONFIRMATION TEST
Go to Next Step.
END