How can I resolve an issue with the adaptive cruise control in a 2020 Toyota Highlander?

Toyota Highlander Fourth Generation (2020-present)

Error Codes

medium

Difficulty

medium

Severity

3 min read

572 words

Problem Statement

Learn how to diagnose and repair adaptive cruise control issues in a 2020 Toyota Highlander, including symptoms, diagnostic steps, and tools required.

Affected Component

Adaptive Cruise Control System

Symptoms

•ACC indicator light is illuminated on the dashboard
•ACC fails to maintain the set speed
•ACC does not respond to the brake pedal
•Warning messages are displayed on the Multi-Information Display (MID)
•The system may turn off unexpectedly or not engage at all

Diagnostic Steps

1
Check for any visible damage to the radar sensor located behind the front grille
2
Inspect the windshield for cracks or obstructions that may affect the camera used for ACC
3
Use an OBD-II scanner to retrieve any stored DTCs related to the ACC system
4
Ensure that the ACC system is activated in the vehicle settings
5
Check if the cruise control system is functioning properly by engaging the regular cruise control
6
Ensure that the radar sensor is properly aligned and calibrated

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

•OBD-II scanner
•Torque wrench
•Multimeter
•Screwdrivers (Phillips and flathead)
•Trim removal tools
•Safety goggles
•Gloves

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Diagnostic Steps

1
Check for any visible damage to the radar sensor located behind the front grille
2
Inspect the windshield for cracks or obstructions that may affect the camera used for ACC
3
Use an OBD-II scanner to retrieve any stored DTCs related to the ACC system
4
Ensure that the ACC system is activated in the vehicle settings
5
Check if the cruise control system is functioning properly by engaging the regular cruise control
6
Ensure that the radar sensor is properly aligned and calibrated

Solution

Issue: Adaptive Cruise Control Malfunction in a 2020 Toyota Highlander

Tools Required

OBD-II scanner
Torque wrench
Multimeter
Screwdrivers (Phillips and flathead)
Trim removal tools
Safety goggles
Gloves

Repair Instructions

Step 1: Retrieve and Analyze Codes

Connect the OBD-II scanner to the vehicle's diagnostic port, typically located under the dashboard.
Turn on the ignition without starting the engine.
Scan for CODES related to the Adaptive Cruise Control system.
Write down any relevant codes for further analysis.

Step 2: Visual Inspection

Inspect the radar sensor for any physical damage or debris obstructing its view.
Clean the area around the radar sensor and the windshield if there are any obstructions.
Look for damaged wiring or connectors related to the ACC system.

Step 3: Sensor Alignment Check

If the radar sensor is misaligned, refer to the service manual for the proper alignment procedure.
Use a torque wrench to ensure that the sensor mounting bolts are tightened to the manufacturer’s specifications.

Step 4: Electrical Testing

Use a multimeter to check the power and ground signals at the radar sensor connector.
Compare the readings to the specifications in the service manual.
Repair any faulty wiring or connectors as necessary.

Step 5: System Calibration

If the radar sensor was replaced or unaligned, perform a calibration procedure as outlined in the service manual.
This often involves using specialized diagnostic equipment or software.

Step 6: Clear DTCs

After repairs or adjustments are made, clear any DTCs using the OBD-II scanner.
Verify that the adaptive cruise control system is functioning correctly by performing a test drive.

Step 7: Final Testing

Engage the adaptive cruise control at a safe speed on a clear stretch of road.
Ensure that the system maintains speed and adjusts according to traffic.
Monitor for any warning lights or messages during the test drive.

Conclusion

If after following these steps the adaptive cruise control system still does not function as expected, it may be necessary to consult a Toyota dealership or a qualified automotive technician for further diagnosis and potential software updates. The ACC system can be complex, and advanced diagnostic tools may be required to pinpoint more obscure issues.