Cruise Control: Other Lexus LS IV

PRECAUTION

1. NOTICE FOR INITIALIZATION NOTE: When disconnecting the cable from the negative (-) battery terminal, initialize the following system after the cable is reconnected. SYSTEM NAME REFERENCE CHART System Name See procedure Navigation System (for DVD) «INITIALIZATION»(ref-349706-S07943075812009120800000) Advanced Parking Guidance System Power Trunk Lid System Rear Door Sunshade System
2. HANDLING PRECAUTION FOR CRUISE CONTROL SYSTEM Turn the cruise control main switch OFF when not using the cruise control system. Be careful as the vehicle speed increases when driving downhill with the cruise control system on. The RESUME/ACCEL operation changes according to the cruise control system status. When the cruise control system is operating, ACCEL operates. When the cruise control system is not operating, RESUME operates. When the cruise control system is operating and the CRUISE main indicator light blinks, turn the cruise control main switch OFF to reset the cruise control system. After the reset, if the cruise control main switch cannot be turned ON, or the cruise control system is canceled immediately after turning the cruise control main switch ON, the system may have a malfunction. Do not use the cruise control system where the road conditions are as follows: Heavy traffic Steep downhill Roads with sharp turns Icy or snowy roads Slippery roads

Scheme 58

Scheme 59

Scheme 60

Communication table

COMMUNICATION CHART

REGISTRATION

1. PERFORM ELECTRONICALLY CONTROLLED BRAKE SYSTEM RECOGNITION IN ECM NOTE: If the vehicle has both cruise control and electronically controlled brake system, when replacing the ECM, perform electronically controlled brake system recognition as follows: Turn the engine switch on (IG). After waiting approximately 5 seconds, turn the cruise control switch ON. Keep the cruise control switch ON for approximately 5 seconds or more.

FAIL-SAFE CHART

HINT

If the following conditions are detected while the cruise control is in operation, the system clears the stored vehicle speed in the ECM and cancels the cruise control operation.

FAIL-SAFE CHART

1. NOTICE FOR INITIALIZATION NOTE: When disconnecting the cable from the negative (-) battery terminal, initialize the following system(s) after the cable is reconnected. SYSTEM NAME REFERENCE CHART System Name See procedure Navigation System (for DVD) «INITIALIZATION»(ref-349706-S07943075812009120800000) Advanced Parking Guidance System Power Trunk Lid System Rear Door Sunshade System Keep in mind the following points when inspecting the dynamic radar cruise control system. As there is a limitation on the vehicle-to-vehicle distance controlling capability, do not overly rely on the dynamic radar cruise control system. Pay constant attention to the vehicle-to-vehicle distance and the traffic conditions when using the dynamic radar cruise control system. Decelerate with the brake pedal, or accelerate with the accelerator pedal, according to the situation, to keep an appropriate distance with the vehicle in front. When the vehicle in front decelerates rapidly or another vehicle moves in front of your vehicle, decelerating in time to avoid a collision may not be possible without additional braking. The dynamic radar cruise control system is designed to assist in maintaining an appropriate distance with the vehicle in front. However, the system alone is not sufficient. It is imperative that the driver pays attention at all times. The millimeter wave radar sensor has functions to automatically detect dirt on the sensor face and inform the driver, but is not perfect. Keep the sensor face clean. The dynamic radar cruise control system does not work, or give a vehicle-approaching warning, for vehicles which are stopped or driving at significantly slower speeds. Always pay attention to these vehicles. The millimeter wave radar sensor detection area is narrow at close range, so detection of a vehicle moving just in front may be delayed, or a motorcycle running on the side of the same lane may not be detected. The distance to the vehicle in front may not be maintained properly due to these reasons. Even if ACCEL is operated to increase the set vehicle speed, the vehicle does not accelerate because the speed is controlled in accordance with the speed of the vehicle in front while driving with the vehicle-to-vehicle distance control mode on (follow-up cruising). However, as the set vehicle speed has been increased by ACCEL operation, the vehicle keeps accelerating when there is no vehicle in front. Check the set speed with the set vehicle speed indication on the display. The controlled vehicle distance may be shorter than the set vehicle distance when cruising on a long downhill road. The cruise control main switch must be turned OFF and then ON if all of the following occur: 1) the CRUISE main indicator light blinks, 2) the master warning light illuminates at the same time as a "pong" sound, and 3) the fail message is shown on the display. The warning buzzer does not sound in the constant speed control mode because the presence of the vehicle in front and the distance to it are not judged as in the vehicle-to-vehicle distance control mode. Pay attention to the distance to the vehicle in front. The dynamic radar cruise control system has 2 cruise control modes: the constant speed control mode and vehicle-to-vehicle distance control mode. Confirm which mode is selected when using the dynamic radar cruise control system.
2. PRECAUTIONS WHEN REPLACING DRIVING SUPPORT ECU If the driving support ECU has been replaced, turn the engine switch off --> on (IG) for 10 seconds --> off to perform the initialization.

Scheme 61

Scheme 62

Scheme 63

Communication table

COMMUNICATION CHART

Scheme 64

1. GENERAL The dynamic radar cruise control system has 2 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 the dynamic radar cruise control system. Operation of the constant speed control mode is the same as the cruise control system. 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 driving 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. 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 using a constant speed function, deceleration cruising function, follow-up cruising function and acceleration cruising function. The front millimeter wave radar sensor and the driving support ECU control the system while the vehicle-to-vehicle distance control mode is in operation, and send signals to each actuator and ECU. 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. This system judges the presence 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 light when approaching the vehicle in front. The following illustration shows an example under the following conditions: your vehicle speed is 100 km/h (62 mph) and the speed of the vehicle in front is 80 km/h (50 mph). Setting of the vehicle distance can be changed to 3 distances by operating the distance control switch (distance control switch): long (approximately 75 m (246 ft.)), middle (approximately 50 m (164 ft.)), and short (approximately 35 m (110 ft.)) when the 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 MAIN COMPONENTS FUNCTION CHART Item Outline Combination meter (CRUISE main indicator light) Turns on when cruise control switch is ON If driving support ECU detects malfunction, this light flashes to warn driver Combination meter (Master warning light) If driving support ECU or ECM detects automatic cancel signal while vehicle is operating under cruise control, this light comes on to inform driver Combination meter (Buzzer) If driving support ECU or ECM detects automatic cancel signal while vehicle is operating under cruise control, this buzzer sounds only once to inform driver Combination meter (Multi-information display) While system is in vehicle-to-vehicle distance control mode, multi-information display receives signals from driving support ECU, in order to display system conditions in graphic area If driving support ECU or ECM detects malfunction signal while vehicle is operating under cruise control, warning message will be displayed in warning area to inform driver Cruise control switch (Main switch) Turns cruise control system ON/OFF Cruise control switch (Control switch) Vehicle speed setting, deceleration setting, preset speed resumption, acceleration setting, and canceling signals are output to driving support ECU through operation of this switch Switches control mode: constant speed control mode and vehicle-to-vehicle distance mode Steering pad switch (Distance control switch) While system is in vehicle-to-vehicle distance control mode, driver can operate steering pad switch (distance control switch) to select vehicle-to-vehicle distance in three stages: long, middle, and short Stop light switch Detects depressing of brake pedal and transmits its signal to driving support ECU Combination switch (Wiper switch) Transmits wiper control switch information to driving support ECU Front millimeter wave radar sensor Radiates radar waves forward, uses reflected waves for detecting presence of vehicle in front, vehicle-to-vehicle distance, and relative speed, and transmits this information to driving support ECU Vehicle speed sensor Vehicle speed signal which is output from skid control ECU is sent to driving support ECU via meter Steering angle sensor Detects angle and direction of steering and transmits its signal to driving support ECU Yaw rate sensor Detects yaw rate of vehicle and transmits its signal to driving support ECU Rain sensor This sensor detects raindrops, and when wiper operates at HI, it requests driving support ECU to transmit cruise control cancel signal Skid control ECU Actuates brakes in accordance with signals from skid control ECU While system is in vehicle-to-vehicle distance control mode, skid control ECU actuates brake actuator in accordance with brake request signal received from driving support ECU Upon receiving signal from driving support ECU, skid control ECU sounds skid control buzzer Skid control buzzer This buzzer sounds upon receiving signal from skid control ECU ECM Controls dynamic radar cruise control system in accordance with signals from switches, sensors, and driving support ECU If driving support ECU detects malfunction in dynamic radar cruise control system, it will output DTCs (Diagnostic Trouble Codes) Throttle position sensor and motor Upon receiving signal from ECM, throttle control motor actuates throttle valve Driving support ECU While system is in vehicle-to-vehicle distance control mode, driving support ECU detects vehicle in front based on signal from front millimeter wave radar sensor. Then, driving support ECU calculates acceleration or deceleration rate in order to attain target vehicle-to-vehicle distance, and outputs request signal to driving support ECU and skid control ECU.
3. LIMIT CONTROL Low speed limit The lowest possible limit of the speed setting range is set at approximately 40 km/h (25 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 when the vehicle speed decreases below the low speed limit (40 km/h (25 mph)) while the cruise control is in operation. When the vehicle speed is increased above the low speed limit after the cruise control operation is canceled, pressing the RESUME switch increases the vehicle speed to the stored speed. High speed limit (Vehicle-to-vehicle distance control mode) The highest possible limit of the speed setting range is approximately 135 km/h (85 mph). The cruise control system cannot be set when the driving vehicle speed is over the high speed limit. Also, RESUME/ACCEL cannot be used to increase speed beyond the high speed limit. High speed limit (Constant speed control mode) The highest possible limit of the speed setting range is approximately 200 km/h (125 mph). The cruise control system cannot be set when the driving vehicle speed is over the high speed limit. Also, RESUME/ACCEL cannot be used to increase speed beyond the high speed limit.
4. CRUISE CONTROL OPERATION The cruise control switch operates 8 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 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 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 the cruise control system. MODE CONTROL Pushing the switch to MODE for more than 1 second while driving with the cruise control switch ON-OFF button on (RADAR READY is on) switches the mode to the constant speed control mode. 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 switch ON (RADAR READY is on), and entering the constant speed control mode. 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 switch ON (RADAR READY is on), and vehicle speed is within the set speed range (between the low and high speed limits). COAST CONTROL (Constant speed control mode) When the cruise control switch is set to SET/COAST and held in that position while the cruise control system is operating, the driving support ECU sends a "throttle valve opening angle 0°" demand signal to the cruise control system. Then the vehicle speed, when the cruise control switch is released, is stored and maintained. HINT: An actual throttle valve opening angle of 0° is not possible due to the idle speed control, etc. COAST CONTROL (Vehicle-to-vehicle distance control mode) When SET/COAST on the cruise control 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 or 5 mph. TAP-DOWN CONTROL (Vehicle-to-vehicle distance control mode) When tapping down the cruise control switch to SET/COAST (for approximately 0.5 seconds) while the constant speed control mode is in operation, the stored vehicle speed decreases each time by approximately 1 km/h or 1 mph. TAP-DOWN CONTROL (Constant speed control mode) When tapping down the cruise control switch to SET/COAST (for approximately 0.5 seconds) while the constant speed control mode is in operation, the stored vehicle speed decreases each time by approximately 1.6 km/h (1 mph). When the cruise control switch is released from SET/COAST and the difference between the driving and stored vehicle speed is more than 5 km/h (3 mph), the vehicle speed is stored and constant speed control is maintained. ACCELERATION CONTROL (Constant speed control mode) The throttle valve motor of the throttle position sensor and motor is instructed by the driving support ECU to open the throttle valve when RESUME/ACCEL on the cruise control switch is pressed and held while the constant speed control mode is in operation. When the cruise control switch is released from RESUME/ACCEL, the vehicle speed is stored and constant speed control is maintained. ACCELERATION CONTROL (Vehicle-to-vehicle distance control mode) When RESUME/ACCEL on the cruise control 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 or 5 mph per second. Pushing the cruise control switch to RESUME/ACCEL while following the vehicle in front with the vehicle-to-vehicle distance control mode on does not increase the actual vehicle speed, but changes only the set vehicle speed. TAP-UP CONTROL (Vehicle-to-vehicle distance control mode) When tapping up the cruise control switch to RESUME/ACCEL (approximately 0.5 seconds) while the constant speed control mode is in operation, the stored vehicle speed increases each time by approximately 1 km/h or 1 mph. TAP-UP CONTROL (Constant speed control mode) When tapping up the cruise control switch to RESUME/ACCEL (approximately 0.5 seconds) 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. MANUAL CANCEL CONTROL Performing any of the following cancels the cruise control system while it is in operation (the stored vehicle speed in the driving support ECU is maintained). Depressing the brake pedal Moving the shift lever to any position except D (8th, 7th, 6th, 5th, and 4th gear) Pulling the cruise control switch to CANCEL Pushing the cruise control switch OFF RESUME CONTROL If the cruise control operation was canceled with the stop light switch or the CANCEL switch, and if driving speed is within the set speed range, pushing the cruise control switch to RESUME/ACCEL restores the vehicle speed memorized at the time of cancellation, and maintains constant speed control.
5. BRAKE CONTROL The driving support ECU determines the distance to the vehicle in front, relative speed, target decreasing speed and deceleration rate. Based on the data, the ECU may transmit a brake demand signal to the skid control ECU.
6. DOWN SHIFT CONTROL When the cruise control system is operating while driving uphill, the gear may down-shift from overdrive (8th gear) to 7th gear. If the gear downshifts to 4th gear and the system receives a signal from the ECT informing that the incline has decreased, the gear automatically returns to overdrive (8th gear). When the cruise control system is operating while driving downhill, the gear may down-shift from overdrive (8th gear) to 7th gear. The driving support ECU receives the vehicle speed sensor signal and calculates the increasing speed rate. Based on this calculation, the ECU downshifts to 4th gear.
7. AUTO CANCEL (FAIL-SAFE) This system has an automatic cancellation function (failsafe) (see «FAIL-SAFE CHART»(ref-349744-S30938353712009120800000) ).

INITIALIZATION

1. INITIALIZE DRIVING SUPPORT ECU If the driving support ECU has been replaced, turn the engine switch off --> on(IG) for 10 seconds --> off to perform the initialization.

Scheme 65

Scheme 66

1. REMOVE FRONT DOOR SCUFF PLATE LH (See «REMOVAL»(ref-349734-S03706653952009120800000) )
2. REMOVE COWL SIDE TRIM BOARD LH (See «REMOVAL»(ref-349734-S03706653952009120800000) )
3. REMOVE DASH PANEL EXTENSION LH Using a clip remover, remove the clip. Disconnect the connector. Remove the 2 nuts and bolt and dash panel extension LH.
4. REMOVE DRIVING SUPPORT ECU Remove the nut and ECU. NOTE: Do not drop or subject the ECU to strong shocks. During the removal and installation, do not remove the drip-proof cover.