LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2021 >> NX 300h Base >> Repair and Diagnosis >> Restraints >> Restraints Control Systems >> Pre-Collision System - Diagnostics - Introduction >> Pre-Collision System >> How To Proceed With Troubleshooting [05/2019 - ] >> Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

How To Proceed With Troubleshooting [05/2019 - ]: Procedure

  1. VEHICLE BROUGHT TO WORKSHOP 

    Result

    Proceed to
    NEXT

    Result: 

    NEXT 

    See step  2

  2. INSPECT AUXILIARY BATTERY VOLTAGE 
    1. Measure the auxiliary battery voltage with the engine switch off.

      Standard voltage

      11 to 14 V (Power switch off)

      If the voltage is below 11 V, replace or recharge the auxiliary battery before proceeding to the next step.

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  3

  3. CHECK MULTI-INFORMATION DISPLAY 
    1. Check if a pre-collision system warning message is displayed on the multi-information display in the combination meter assembly.

      HINT: 

      If more than one warning message is displayed, check in the order of A, B, C and D.

      Result

      Result Proceed to
      "VSC Turned Off Pre-Collision Brake System Unavailable" is displayed A
      "Pre-Collision System Malfunction Visit Your Dealer" is displayed B
      Any of the following messages is displayed:
      • "Pre-Collision System Unavailable"
      • "Pre-Collision System Unavailable Clean Sensor"
      • "Front Camera Unavailable"
      • "Front Camera Vision Blocked Clean and Demist Windshield"
      C
      Pre-collision system warning message is not displayed D

    Result: 

    GO TO PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [05/2019 - ]  

    Result: 

    See step  6

    Result: 

    See step  9

    Result: 

    See step  4

  4. CHECK CAN COMMUNICATION SYSTEM* 
    1. Using the Techstream, check if the CAN communication system is functioning normally.

      Refer to HOW TO PROCEED WITH TROUBLESHOOTING [05/2019 - ]

      OK

      CAN communication system is functioning normally.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    GO TO CAN COMMUNICATION SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [05/2019 - ] 

    Result: 

    OK 

    See step  5

  5. CHECK FOR DTC* (PRE-COLLISION SYSTEM) 
    1. Check for DTCs.

      Refer to DTC CHECK / CLEAR [05/2019 - ] 

      Body Electrical > Pre-Collision System > Trouble Codes 

      Result

      Result Proceed to
      DTCs are not output A
      DTC C142571 is output B
      A DTC other than C142571 is output C

    Result: 

    GO TO DTC CHART (C142571). Refer to  DTC C1425-71: Stop Light Relay Actuator Stuck [05/2019 - ] 

    Result: 

    See step  8

    Result: 

    See step  6

  6. CHECK FOR VEHICLE CONTROL HISTORY* (PRE-COLLISION SYSTEM) 
    1. Check for vehicle control history and note any codes that are output.

      Refer to VEHICLE CONTROL HISTORY [05/2019 - ]

      Body Electrical > Pre-Collision System > Utility 

      Tester Display
      Vehicle Control History (RoB)
      1. Record the vehicle control history.

      Result

      Result Proceed to
      Vehicle control history is not output A
      X2006, X2013, X2015, X2022, X2024, X2025, X2026 or X2028 is output B
      Vehicle control history other than X2006, X2013, X2015, X2022, X2024, X2025, X2026 and X2028 is output C

    Result: 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [05/2019 - 10/2019]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2019 - 07/2020]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [07/2020 - ] 

    Result: 

    GO TO VEHICLE CONTROL HISTORY. Refer to  VEHICLE CONTROL HISTORY [05/2019 - ] 

    Result: 

    See step  7

  7. CHECK FOR VEHICLE CONTROL HISTORY* (PRE-COLLISION SYSTEM) 
    1. Clear the vehicle control history.

      Refer to VEHICLE CONTROL HISTORY [05/2019 - ]

      Body Electrical > Pre-Collision System > Utility 

      Tester Display
      Vehicle Control History (RoB)
    2. Recheck for vehicle control history.
      1. Check if the following vehicle control history is output.

        Refer to VEHICLE CONTROL HISTORY [05/2019 - ]

        Body Electrical > Pre-Collision System > Utility 

        Tester Display
        Vehicle Control History (RoB)

      Result

      Result Proceed to
      Vehicle control history is not output A
      Vehicle control history is output B

    Result: 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [05/2019 - 10/2019]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2019 - 07/2020]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [07/2020 - ] 

    Result: 

    GO TO VEHICLE CONTROL HISTORY. Refer to  VEHICLE CONTROL HISTORY [05/2019 - ] 

  8. CHECK FOR DTC* (PRE-COLLISION SYSTEM) 
    1. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [05/2019 - ] 

      Body Electrical > Pre-Collision System > Clear DTCs 

    2. Reproduce the detection conditions of the recorded DTC.

      HINT: 

      Refer to the flowchart for the detection conditions for each of the DTCs.

    3. Recheck for DTCs.
      1. Attempt to duplicate the malfunction and check if the DTCs are output again.

        Refer to DTC CHECK / CLEAR [05/2019 - ] 

        Body Electrical > Pre-Collision System > Trouble Codes 

      Result

      Result Proceed to
      DTCs are not output A
      DTC is output B

    Result: 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [05/2019 - 10/2019]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2019 - 07/2020]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [07/2020 - ] 

    Result: 

    GO TO DIAGNOSTIC TROUBLE CODE CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART [05/2019 - ]  

  9. PROBLEM SYMPTOMS TABLE 
    1. Refer to Problem Symptoms Table.

      Refer to PROBLEM SYMPTOMS TABLE [05/2019 - ] 

      Result

      Result Proceed to
      Fault is not listed in Problem Symptoms Table. A
      Fault is listed in Problem Symptoms Table. B

    Result: 

    ADJUST, REPAIR OR REPLACE IN ACCORDANCE WITH PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [05/2019 - ]  

    Result: 

    See step  10

  10. CHECK PCS WARNING LIGHT 
    1. Check the condition of the PCS warning light.

      Result

      Result Proceed to
      Only the PCS warning light is illuminated. A
      The PCS warning light is not illuminated. B

    Result: 

    See step  12

    Result: 

    See step  11

  11. CHECK FOR VEHICLE CONTROL HISTORY* (X2015) 
    1. Check for vehicle control history and note any codes that are output.

      Refer to VEHICLE CONTROL HISTORY [05/2019 - ]

      Body Electrical > Pre-Collision System > Utility 

      Tester Display
      Vehicle Control History (RoB)

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    GO TO VEHICLE CONTROL HISTORY. Refer to  VEHICLE CONTROL HISTORY [05/2019 - ] 

  12. CHECK FOR DTC* (PRE-COLLISION SYSTEM) 
    1. Check for DTCs.

      Refer to DTC CHECK / CLEAR [05/2019 - ] 

      Body Electrical > Pre-Collision System > Trouble Codes 

      Result

      Result Proceed to
      DTCs are not output A
      DTC is output B

    Result: 

    See step  14

    Result: 

    See step  13

  13. CHECK CONFIRMED DTC DETECTION CONDITION* 
    1. Check detection condition for the confirmed pre-collision system DTC.

      Refer to FAIL-SAFE CHART [05/2019 - ] 

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    END 

    1. Explain to the customer the cause of the previously stored DTC and that the output reason has been cleared.
  14. CHECK FOR VEHICLE CONTROL HISTORY* (PRE-COLLISION SYSTEM) 
    1. Check for vehicle control history and note any codes that are output.

      Refer to VEHICLE CONTROL HISTORY [05/2019 - ]

      Body Electrical > Pre-Collision System > Utility 

      Tester Display
      Vehicle Control History (RoB)
      1. Record the vehicle control history.

      Result

      Result Proceed to
      Vehicle control history is not output A
      Vehicle control history is output B

    Result: 

    See step  16

    Result: 

    See step  15

  15. CONDITIONS WHEN PRE-COLLISION SYSTEM OPERATE OR NOT OPERATE 
    1. Check the conditions when pre-collision system operates or does not operate.

      Refer to PRECAUTION [05/2019 - ] 

      Result

      Result Proceed to
      Any condition is met. A
      No condition is met. B

    Result: 

    END (OPERATION/NO OPERATION CONDITIONS OF PRE-COLLISION SYSTEM IS MET) 

    Result: 

    See step  17

  16. CHECK FOR VEHICLE CONTROL HISTORY* (PRE-COLLISION SYSTEM) 
    1. Check for vehicle control history and note any codes that are output.

      Refer to VEHICLE CONTROL HISTORY [05/2019 - ]

      HINT: 

      Based on the customer's inquiry, check the corresponding factors in the vehicle control history, such as the detection time and date, trip information and elapsed time.

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    END 

    1. Explain to the customer the cause of the previously stored vehicle control history and that the output reason has been cleared.
  17. INSPECT MILLIMETER WAVE RADAR SENSOR ASSEMBLY* (FRONT BEAM AXIS MISALIGNMENT READING) 
    NOTE:

    Before performing beam axis adjustment, check the fitting of the front bumper cover and radiator grille assembly and confirm that there is no warping or deformation.

    1. Adjust the reflector height.

      Refer to ADJUSTMENT [05/2019 - ]

    2. Place the reflector.

      Refer to ADJUSTMENT [05/2019 - ]

    3. Connect the Techstream to the DLC3.
    4. Turn the power switch on (IG).
    5. Turn the Techstream on.
    6. Turn the cruise control main switch on.
    7. Enter the following menus: Body Electrical / Front Radar Sensor / Utility / Front Beam Axis Misalignment Reading.

      Body Electrical > Front Radar Sensor > Utility 

      Tester Display
      Front Beam Axis Misalignment Reading
    8. Check the amount of misalignment and make a note.

      Standard (before performing adjustment)

      Front beam axis misalignment value 

      Vertical -5.0 to 5.0 deg.
      Horizontal -0.6 to 0.6 deg.

      Result

      Result Proceed to
      Front beam axis misalignment value is within the specified range. A
      Front beam axis misalignment value is not within the specified range. B

    Result: 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [05/2019 - 10/2019]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2019 - 07/2020]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [07/2020 - ] 

    Result: 

    PERFORM FRONT BEAM AXIS ADJUSTMENT. Refer to  ADJUSTMENT [05/2019 - ]