What could cause my 2021 Toyota Highlander to have a malfunctioning cruise control?

Toyota Highlander Fourth Generation (2020-present)

Error Codes

medium

Difficulty

medium

Severity

4 min read

782 words

Problem Statement

Learn how to diagnose and repair the malfunctioning cruise control system in your 2021 Toyota Highlander with detailed steps and required tools.

Affected Component

Cruise Control System

Symptoms

•Cruise Control Light Not Illuminating
•Inability to Set Speed
•Cruise Control Disengages Unexpectedly
•Erratic Speed Control

Diagnostic Steps

1
Visual Inspection
2
Scan for Diagnostic Trouble Codes (DTCs)
3
Test the Brake Light Switch
4
Inspect the Throttle Position Sensor (TPS)
5
Check the Vehicle Speed Sensor (VSS)
6
Inspect the Cruise Control Module

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
•Basic hand tools (screwdrivers, socket set)

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Solution

Problem Diagnosis: Malfunctioning Cruise Control in 2021 Toyota Highlander

Step 1: Visual Inspection

Tools Required: Flashlight
Check the condition of the cruise control lever or buttons. Look for any visible damage or debris obstructing operation.
Inspect the vehicle's fuses using the fuse panel diagram in the owner's manual. Look specifically for the cruise control fuse.

Step 2: Scan for Diagnostic Trouble Codes (DTCs)

Tools Required: OBD-II Scanner
Connect the OBD-II scanner to the vehicle's diagnostic port (usually located under the steering wheel).
Check for any stored codes related to the cruise control system, such as codes for the throttle position sensor, brake switch, or speed sensor.

Step 3: Test the Brake Light Switch

Tools Required: Multimeter
The cruise control system is designed to disengage when the brake pedal is pressed. A malfunctioning brake light switch can cause cruise control issues.
Use the multimeter to test the brake light switch for continuity when the brake pedal is pressed. If it does not engage, replace the switch.

Step 4: Inspect the Throttle Position Sensor (TPS)

Tools Required: Multimeter or Scan Tool
The TPS sends information about the throttle position to the engine control unit (ECU). If faulty, it can prevent cruise control from functioning.
Check the TPS using a multimeter to ensure it’s within specifications. If you have a scan tool, monitor the TPS readings while manually operating the throttle.

Step 5: Check the Vehicle Speed Sensor (VSS)

Tools Required: Multimeter or Scan Tool
The VSS communicates the vehicle’s speed to the ECU. If it malfunctions, cruise control may not engage or function properly.
Use the multimeter to check the output of the VSS. Alternatively, use a scan tool to check the speed readings while driving.

Step 6: Inspect the Cruise Control Module

Tools Required: Basic hand tools (screwdrivers, socket set)
Disconnect the cruise control module (usually located near the accelerator pedal or in the engine bay) and inspect the wiring harness for damage.
If necessary, test the module with a multimeter or replace it if it’s found to be non-functional.

Repair Instructions

Repair Option 1: Replace the Brake Light Switch

Disconnect Battery: Remove the negative terminal to prevent electrical shorts.
Locate the Brake Light Switch: Usually mounted above the brake pedal.
Remove the Old Switch: Disconnect the wiring harness and remove any mounting screws or clips.
Install the New Switch: Position the new switch and secure it in place. Reconnect the wiring harness.
Reconnect Battery: Reattach the negative terminal.

Repair Option 2: Replace the Throttle Position Sensor

Disconnect Battery: Ensure safety by disconnecting the negative terminal.
Locate the TPS: Usually mounted on the throttle body.
Remove the Old Sensor: Disconnect the wiring harness and remove screws securing the TPS.
Install the New TPS: Position the new sensor and secure it with screws. Reconnect the wiring harness.
Reconnect Battery: Reattach the negative terminal.

Repair Option 3: Replace the Vehicle Speed Sensor

Disconnect Battery: Again, ensure safety by disconnecting the negative terminal.
Locate the VSS: Typically found on the transmission.
Remove the Old Sensor: Unscrew and disconnect the wiring harness.
Install the New Sensor: Position the new sensor and secure it in place. Reconnect the wiring harness.
Reconnect Battery: Reattach the negative terminal.

Repair Option 4: Replace the Cruise Control Module

Disconnect Battery: Remove the negative terminal.
Locate the Cruise Control Module: Refer to the service manual for the exact location.
Remove the Module: Disconnect the wiring harness and unscrew any mountings.
Install the New Module: Position the new module and secure it. Reconnect the wiring harness.
Reconnect Battery: Reattach the negative terminal.

Final Steps

Test Drive: After any repairs, take the vehicle for a test drive to verify that the cruise control functions as intended.
Re-scan for DTCs: Use the OBD-II scanner to ensure no new codes have appeared after repairs.

Conclusion

Following these steps will help diagnose and repair the malfunctioning cruise control system in your 2021 Toyota Highlander. If issues persist, consider consulting a professional technician for further diagnosis.