Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual: Problem Symptoms Table

PROBLEM SYMPTOMS TABLE

NOTICE:

  • Before replacing the ECM, refer to Registration.

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  • When replacing the millimeter wave radar sensor assembly, always replace it with a new one. If a millimeter wave radar sensor assembly which was installed to another vehicle is used, the information stored in the millimeter wave radar sensor assembly will not match the information from the vehicle and a DTC may be stored.
  • When the millimeter wave radar sensor assembly has been replaced with a new one, it is necessary to perform millimeter wave radar sensor assembly adjustment and front radar acceleration sensor calibration, and to clear the vehicle control history.

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  • When replacing the forward recognition camera, replace it with a new one. If a forward recognition camera which was installed to another vehicle is used, the information stored in the forward recognition camera will not match the information from the vehicle and a DTC may be stored.
  • If the forward recognition camera has been replaced with a new one or the windshield glass has been removed and installed, it is necessary to perform forward recognition camera adjustment.

    HINT:

    Forward recognition camera adjustment can be performed by using either One Time Recognition or Sequential Recognition.

    One Time Recognition: Click here

    Sequential Recognition: Click here

HINT:

  • Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of probability in the "Suspected Area" column of the table. Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.
  • Inspect the fuses and relays related to this system before inspecting the suspected areas below.
  • Determine the problem systems, then perform the respective inspection procedures.
  • By using the vehicle control history, various control parameter history can be checked.
Dynamic Radar Cruise Control System

Symptom

Suspected Area

Link

The dynamic radar cruise control system cannot be turned on using the cruise control main switch

CAN communication system

Cruise control switch circuit

Cruise main indicator light circuit

Forward recognition camera

ECM

The dynamic radar cruise control mode cannot be changed between vehicle-to-vehicle distance control mode and constant speed control mode

CAN communication system

Cruise control switch circuit

ECM

The vehicle-to-vehicle distance cannot be changed

CAN communication system

Distance control switch circuit

Forward recognition camera

Vehicle speed setting cannot be performed (in constant speed control mode)

Fail-safe chart

CAN communication system

Cruise control switch circuit

Stop light switch circuit

Automatic transaxle system (for U881E)

Automatic transaxle system (for U881F)

Vehicle stability control system

Forward recognition camera

ECM

Vehicle speed setting cannot be performed (in vehicle-to-vehicle distance control mode)

Front Radar Sensor Temporary Unavailable (Optical Axis Misalignment) history*

Fail-safe chart

Forward recognition camera is temporarily unavailable

Millimeter wave radar sensor assembly is dirty

Millimeter wave radar sensor assembly beam axis not adjusted

CAN communication system

Cruise control switch circuit

Automatic transaxle system (for U881E)

Automatic transaxle system (for U881F)

Millimeter wave radar sensor assembly

Forward recognition camera

Vehicle stability control system

ECM

Control of vehicle speed by the dynamic radar cruise control system is canceled (in constant speed control mode)

Fail-safe chart

CAN communication system

Cruise control switch circuit

Stop light switch circuit

Automatic transaxle system (for U881E)

Automatic transaxle system (for U881F)

Vehicle stability control system

ECM

Control of vehicle speed by the dynamic radar cruise control system is canceled (in vehicle-to-vehicle distance control mode)

Fail-safe chart

Forward recognition camera is temporarily unavailable

Millimeter wave radar sensor assembly is dirty

Millimeter wave radar sensor assembly beam axis not adjusted

CAN communication system

Cruise control switch circuit

Automatic transaxle system (for U881E)

Automatic transaxle system (for U881F)

Millimeter wave radar sensor assembly

Forward recognition camera

Vehicle stability control system

ECM

Hunting/vehicle speed is not constant (in constant speed control mode)

CAN communication system

Vehicle stability control system

ECM

Hunting/vehicle speed is not constant (in vehicle-to-vehicle distance control mode)

Millimeter wave radar sensor assembly is dirty

Millimeter wave radar sensor assembly beam axis not adjusted

CAN communication system

Vehicle stability control system

Millimeter wave radar sensor assembly

ECM

Vehicle speed control by the dynamic radar cruise control system is not canceled when the CANCEL switch is pushed

Cruise control switch circuit

ECM

Moving the shift lever does not cancel control of vehicle speed by the dynamic radar cruise control system

Park/neutral position switch assembly (for U881E)

Park/neutral position switch assembly (for U881F)

Transmission floor shift assembly (for U881E)

Transmission floor shift assembly (for U881F)

Automatic transaxle system (for U881E)

Automatic transaxle system (for U881F)

ECM

Vehicle speed control by the dynamic radar cruise control system is not canceled when a shift paddle switch is operated

Automatic transaxle system (for U881E)

Automatic transaxle system (for U881F)

Shift paddle switch circuit (for U881E)

Shift paddle switch circuit (for U881F)

ECM

Depressing the brake pedal does not cancel control of vehicle speed by the dynamic radar cruise control system

Stop light switch circuit

ECM

Control cannot be canceled while the vehicle is stopped

CAN communication system

Vehicle stability control system

Electric parking brake system

Seat belt warning system

Door courtesy switch circuit

ECM

Control cannot be canceled by operating the parking brake

Electric parking brake system

CAN communication system

Skid control ECU (brake actuator assembly)

ECM

Even though the millimeter wave radar sensor assembly and forward recognition camera are not dirty, the warning message "Radar Cruise Control Unavailable See Owner's Manual" is displayed

Millimeter wave radar sensor assembly

Forward recognition camera

The vehicle approach warning buzzer does not sound

Skid control buzzer assembly

Check millimeter wave radar sensor assembly installation position

Check installation of forward recognition camera

Forward recognition camera

Millimeter wave radar sensor assembly

Even though the vehicle approach warning buzzer is sounding, brake control is not performed to decelerate the vehicle

Vehicle stability control system

CAN communication system

Forward recognition camera

ECM

Even though the SET function is operating, the cruise SET indicator does not illuminate

CAN communication system

Cruise SET indicator light circuit

ECM

The cruise control indicator remains illuminated

CAN communication system

Cruise main indicator light circuit

ECM

Indicators are not displayed on the multi-information display in the combination meter assembly

CAN communication system

ECM

A buzzer does not sound when control of vehicle speed by the dynamic radar cruise control is canceled

CAN communication system

ECM

  • *: When "Radar Cruise Control Unavailable" is displayed and there is "Front Radar Sensor Temporary Unavailable (Optical Axis Misalignment)" history, the beam axis of the millimeter wave radar sensor assembly may be being aligned. In this case, wait for beam axis alignment to complete. When beam axis alignment is complete, "Radar Cruise Control Unavailable" stops being displayed.
    Operation Check
    OPERATION CHECK INPUT SIGNAL CHECK (a) Connect the Techstream to the DLC3. (b) Check the cruise control main switch using the Data List function of the Techstream (ON-OFF, -SET, +RES and CANCEL). ...

    Diagnosis System
    DIAGNOSIS SYSTEM DIAGNOSIS FUNCTION (a) The diagnosis function turns off the cruise control indicator, illuminates the master warning light and displays a warning message when a malfunction is detecte ...

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    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Owners Manual

    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Repair Manual

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