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How can I troubleshoot issues with the automatic start-stop system in a 2020 Highlander? - Toyota Highlander
Home/Cars/Toyota/Highlander/Fourth Generation (2020-present)/How can I troubleshoot issues with the automatic start-stop system in a 2020 Highlander?

How can I troubleshoot issues with the automatic start-stop system in a 2020 Highlander?

Toyota Highlander Fourth Generation (2020-present)

Error Codes
2-3 hours
Time
medium
Difficulty
medium
Severity
Navigation
ProblemSymptomsDiagnosisSolution
ProblemSymptomsDiagnosisSolution
4 min read
638 words

Problem Statement

Learn how to troubleshoot issues with the automatic start-stop system in a 2020 Toyota Highlander, including symptoms, diagnostic steps, and repair instructions.

Affected Component
automatic start-stop system
Estimated Time
2-3 hours

Symptoms

  • •Engine does not turn off at idle
  • •Engine does not restart automatically
  • •Warning lights
  • •System intermittently works

Diagnostic Steps

  1. 1
  2. 2
  3. 3
  4. 4
  5. 5

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

  • •Multimeter
  • •Fuse puller or pliers
  • •OBD-II Scanner

Additional Information

Affected Component
automatic start-stop system
Estimated Time
2-3 hours
Difficulty
medium
Severity
medium
Tools Required
3 items

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Troubleshooting Automatic Start-Stop System in a 2020 Toyota Highlander

The automatic start-stop system in the 2020 Toyota Highlander is designed to enhance fuel efficiency by shutting off the engine at idle and restarting it when needed. If you’re experiencing issues with this system, follow these detailed steps to diagnose and potentially fix the problem.

Step 1: Visual Inspection

  1. Check the Battery Condition

    • Symptoms: If the battery is weak or not holding a charge, the start-stop system will be disabled.
    • Tool Required: Multimeter
    • Instructions:
      • Use a multimeter to check voltage. A healthy battery should read approximately 12.6 volts or higher when the engine is off.

  2. Inspect Battery Connections

    • Symptoms: Loose or corroded connections can affect performance.
    • Instructions:
      • Check the battery terminals for any corrosion or looseness. Clean any corrosion with a wire brush and reconnect firmly.

  3. Examine Fuses and Relays

    • Symptoms: A blown fuse can disable the system.
    • Tool Required: Fuse puller or pliers
    • Instructions:
      • Locate the fuse box (check the owner’s manual for location) and inspect the fuses associated with the start-stop system. Replace any blown fuses as necessary.

Step 2: Check the Start-Stop System Settings

  1. Confirm System Activation
    • Symptoms: The system may be deactivated by settings.
    • Instructions:
      • Navigate to the vehicle settings using the infotainment system. Ensure the start-stop feature is enabled in the vehicle settings.

Step 3: Diagnostic Scan

  1. Perform a Diagnostic Scan
    • Symptoms: If there are faults in the system, they will be logged in the ECU.
    • Tool Required: OBD-II Scanner
    • Instructions:
      • Connect the OBD-II scanner to the vehicle's diagnostic port (usually located under the dashboard).
      • Retrieve any trouble codes related to the start-stop system. Note any codes for further diagnosis.
Repair Instructions

Step 1: Address Battery Issues

  1. Replace the Battery (if needed)
    • If the battery voltage is low or if it’s unable to hold a charge, replace it with a compatible battery.

Step 2: Clear Fault Codes

  1. Reset the ECU
    • After addressing any issues, clear the fault codes using the OBD-II scanner.
    • Instructions:
      • Follow the scanner’s instructions to erase codes, then turn off the vehicle for a few minutes.

Step 3: Inspect Additional Components

  1. Check the Brake System

    • The start-stop system relies on the brake system. If the brake pedal position switch is faulty, it may prevent the engine from turning off.
    • Symptoms: Engine does not turn off when the brake is engaged.
    • Tool Required: Multimeter
    • Instructions:
      • Test the brake pedal switch with a multimeter. Replace if faulty.

  2. Inspect the Starter and Alternator

    • If the starter is malfunctioning, it may not restart the engine properly.
    • Symptoms: No response from the starter when attempting to restart.
    • Instructions:
      • Test the starter and alternator for correct operation. Replace any faulty components.

Step 4: Consult Technical Service Bulletins (TSBs)

  1. Check for TSBs Related to Start-Stop System
    • Visit the Toyota website or contact your local dealership for any TSBs that may address known issues with the start-stop system.
Conclusion

If, after following these steps, the automatic start-stop system still does not function properly, it may be best to consult with a qualified Toyota technician. They will have access to specialized diagnostic equipment and can perform more in-depth analysis to identify and resolve complex issues.