FAULTBASE
Error CodesASKCars
© 2026 FAULTBASE
All rights reserved.
v2.0.0 • Production
ContactPrivacyImpressum
How do I troubleshoot the adaptive cruise control system in a 2020 Highlander? - Toyota Highlander
Home/Cars/Toyota/Highlander/Fourth Generation (2020-present)/How do I troubleshoot the adaptive cruise control system in a 2020 Highlander?

How do I troubleshoot the adaptive cruise control system in a 2020 Highlander?

Toyota Highlander Fourth Generation (2020-present)

Error Codes
medium
Difficulty
medium
Severity
Navigation
ProblemSymptomsDiagnosisSolution
ProblemSymptomsDiagnosisSolution
3 min read
590 words

Problem Statement

Learn how to troubleshoot the Adaptive Cruise Control system in your 2020 Toyota Highlander with detailed steps and required tools.

Affected Component
Adaptive Cruise Control System

Symptoms

  • •ACC not engaging or disengaging unexpectedly
  • •Warning lights on the instrument cluster (e.g., ACC warning light)
  • •Inconsistent speed control (accelerating or decelerating erratically)
  • •Failure to maintain set distance from the vehicle ahead
  • •System not recognizing vehicles

Diagnostic Steps

  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7
  8. 8

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

  • ✓Test the affected component to ensure it functions correctly
  • ✓Check for any error codes or warning lights
  • ✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

  • •Follow the manufacturer's recommended maintenance schedule
  • •Address warning signs early before they develop into major issues
  • •Use quality parts and fluids recommended for your vehicle
  • •Keep detailed records of all repairs and maintenance

Tools & Equipment Required

  • •Flashlight
  • •OBD-II scanner
  • •Multimeter
  • •Wiring diagrams (from repair manual)

Additional Information

Affected Component
Adaptive Cruise Control System
Difficulty
medium
Severity
medium
Tools Required
4 items

Related Faults

Loading...

Share this solution

Comments

Sign in to share your thoughts

Sign In

No comments yet

Be the first to share your thoughts

Back to Generation

Troubleshooting the Adaptive Cruise Control System in a 2020 Toyota Highlander

Adaptive Cruise Control (ACC) is a convenient feature in modern vehicles that automatically adjusts the speed to maintain a safe distance from the car in front. If you are experiencing issues with the ACC system in your 2020 Toyota Highlander, follow these detailed troubleshooting steps.

Step 1: Visual Inspection

Tools Required:

  • Flashlight
  • OBD-II scanner

  1. Inspect the Radar Sensor and Camera:

    • Check the front grille area for any obstructions (dirt, snow, or debris) covering the radar sensor. The sensor is typically located near the front emblem.
    • Ensure there are no physical damages or misalignments with the camera mounted on the windshield.

  2. Check for Warning Lights:

    • Look for any warning lights on the dashboard related to the ACC. If any are present, note them down.
Step 2: OBD-II Scan

Tools Required:

  • OBD-II scanner

  1. Connect the OBD-II Scanner:

    • Plug the scanner into the OBD-II port, usually located under the dashboard near the driver's seat.

  2. Read Error Codes:

    • Access the diagnostic trouble codes (DTCs) related to the ACC system. Look for codes specific to the Adaptive Cruise Control function (e.g., C1201, C1202).

  3. Document Any Codes:

    • Write down all the codes and their descriptions for further analysis.
Step 3: Clear Codes and Test

  1. Clear DTCs:

    • Use the scanner to clear any stored trouble codes.

  2. Test Drive:

    • Take the vehicle for a test drive to see if the ACC system operates normally. Note any occurrences of issues that arise.
Repair Instructions
Step 4: Address Obstructions and Sensor Issues

  1. Clean the Radar Sensor:

    • If dirt or debris is found on the radar sensor, clean it with a microfiber cloth and mild soap solution.

  2. Check Camera Alignment:

    • If misaligned, you may need a professional to recalibrate the camera system.
Step 5: Inspect Wiring and Connectors

Tools Required:

  • Multimeter
  • Wiring diagrams (from repair manual)

  1. Check Wiring:

    • Inspect the wiring harness connected to the radar sensor and camera for frays, corrosion, or loose connections.
    • Use a multimeter to check for continuity in the wires.

  2. Repair or Replace Damaged Wires/Connectors:

    • If any wiring or connectors are damaged, repair or replace them as necessary.
Step 6: Software Update
  1. Check for Software Updates:
    • Using the OBD-II scanner, check if there are any available software updates for the ACC system.
    • If updates are available, follow the manufacturer’s instructions to complete the update.
Step 7: Professional Calibration (if required)
  • If issues persist after performing all the above steps, it may be necessary to take the vehicle to a Toyota dealership or a certified technician for professional calibration of the ACC system.
Step 8: Final Test
  1. Test the ACC Again:
    • After repairs and possible calibrations, conduct another test drive to confirm that the ACC system operates properly.
Conclusion

If the ACC system is still malfunctioning after following these troubleshooting steps, it’s advisable to consult with a certified Toyota technician. Some issues may require more advanced diagnostics or specialized tools that are not available to the average vehicle owner.