What are the common issues with the adaptive cruise control in the 2021 Toyota Highlander?

Toyota Highlander Fourth Generation (2020-present)

Error Codes

medium

Difficulty

medium

Severity

4 min read

675 words

Problem Statement

Learn about the common issues, symptoms, and diagnostic steps for the adaptive cruise control system in the 2021 Toyota Highlander.

Affected Component

adaptive cruise control system

Symptoms

•Cruise Control Not Engaging
•System Disconnects or Turns Off Unexpectedly
•Erratic Speed Adjustments
•Warning Lights or Messages
•Inaccurate Distance Maintenance

Diagnostic Steps

1
Visual Inspection
2
Check System Status
3
Scan for Diagnostic Trouble Codes (DTCs)
4
Test Functionality

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
•Screwdrivers (Philips and Flathead)
•Multimeter
•Cleaning Supplies (e.g., microfiber cloths, glass cleaner)
•Torque Specifications Reference
•Replacement Parts (if needed, based on diagnosis)

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Solution

Common Issues with Adaptive Cruise Control in the 2021 Toyota Highlander

The adaptive cruise control system in the 2021 Toyota Highlander is designed to automatically adjust the vehicle's speed to maintain a safe following distance from the vehicle ahead. However, like any advanced driver assistance system, it can experience issues. Below are common symptoms, diagnostic steps, tools required, and repair instructions for troubleshooting problems with the adaptive cruise control in the 2021 Toyota Highlander.

Common Symptoms

Cruise Control Not Engaging
- The adaptive cruise control system fails to activate when the cruise control button is pressed.
System Disconnects or Turns Off Unexpectedly
- The system is activated but disengages suddenly without user input.
Erratic Speed Adjustments
- The vehicle accelerates or decelerates unexpectedly, failing to maintain a consistent speed.
Warning Lights or Messages
- Dashboard warning lights illuminate, such as the cruise control indicator or a generic warning.
Inaccurate Distance Maintenance
- Fails to maintain the set distance from the vehicle ahead, either getting too close or too far.

Tools Required

OBD-II Scanner
Torque Wrench
Screwdrivers (Philips and Flathead)
Multimeter
Cleaning Supplies (e.g., microfiber cloths, glass cleaner)
Torque Specifications Reference
Replacement Parts (if needed, based on diagnosis)

Repair Instructions

1. Cleaning the Radar Sensor

Step 1: Open the hood and locate the front radar sensor behind the grille.
Step 2: Clean the sensor lens using a microfiber cloth and glass cleaner to ensure clarity.
Step 3: Check for physical damage and ensure it is securely mounted.

2. Checking Electrical Connections

Step 1: Disconnect the vehicle battery to prevent any electrical shorts (negative terminal first).
Step 2: Inspect the wiring harness connected to the radar sensor for frays or disconnection.
Step 3: Use a multimeter to test for continuity in the wiring.
Step 4: Reconnect any loose connections and ensure all plugs are seated properly.

3. Updating Software

Step 1: Using the OBD-II scanner, check if there are any available software updates for the vehicle’s ECU.
Step 2: If an update is available, follow the manufacturer’s instructions to install it.

4. Replacing the Radar Sensor

Step 1: If the radar sensor is diagnosed as faulty, remove it by unscrewing the mounting bolts (ensure to check torque specifications).
Step 2: Disconnect the electrical connector from the sensor.
Step 3: Install the new sensor by reversing the steps, ensuring to torque the bolts to the specified settings.

5. Resetting the System

Step 1: Reconnect the vehicle battery (positive terminal first, then negative).
Step 2: Start the vehicle and check if the adaptive cruise control system is functioning correctly.
Step 3: Clear any DTCs using the OBD-II scanner and perform a test drive.

Conclusion

If, after performing these diagnostic and repair steps, the adaptive cruise control system continues to malfunction, it may require further investigation by a qualified technician or a visit to the dealership. Advanced issues may pertain to the vehicle's ECU or require specialized equipment for calibration and diagnostics.