Are there any issues with the engine start/stop system in the 2021 Toyota Highlander?

Overview of the Engine Start/Stop System in the 2021 Toyota Highlander

The 2021 Toyota Highlander, as part of the fourth generation, comes equipped with an engine start/stop system designed to improve fuel efficiency and reduce emissions. However, like any automotive system, issues may arise. Below are common symptoms, diagnostic steps, tools required, and repair instructions if you encounter problems with the start/stop system.

Common Symptoms

1. Engine Fails to Restart: The engine does not restart after stopping.
2. Warning Lights: Dashboard warning lights (such as the battery or check engine light) illuminate.
3. Inconsistent Operation: The start/stop system engages and disengages erratically.
4. Delayed Engine Shut Off: The engine does not turn off when it should during stops.
5. Battery Warning: A message indicating the battery is low or not charging properly.

Repair Instructions

1. Battery Replacement

   • If the battery is weak or faulty, replace it with a new OEM battery.
   • Follow proper safety precautions, disconnecting the negative terminal first, then the positive.

2. Brake Switch Replacement

   • If the brake switch is malfunctioning, replace it as follows:
     • Locate the brake switch near the brake pedal.
     • Disconnect the electrical connector.
     • Remove the switch retaining clip and pull out the switch.
     • Install the new switch and reconnect the electrical connector.

3. Alternator Repair/Replacement

   • If the alternator is not charging correctly, consider replacement:
     • Disconnect the battery (negative terminal first).
     • Remove the serpentine belt.
     • Disconnect the electrical connectors from the alternator.
     • Remove mounting bolts and take out the alternator.
     • Install the new alternator and reconnect everything in reverse order.

4. Start/Stop System Component Replacement

   • If a relay or control module is faulty:
     • Disconnect the battery to avoid electrical shorts.
     • Remove the faulty relay or module according to the vehicle’s service manual.
     • Install the new part and reconnect the battery.

Final Steps

1. Clear DTCs: After repairs, use the OBD-II scanner to clear any codes.
2. Test Drive: Conduct a test drive to ensure the start/stop system functions correctly.
3. Monitor for Recurrence: Keep an eye on the operation of the start/stop system and any warning lights.

Conclusion

If the engine start/stop system in your 2021 Toyota Highlander exhibits issues, following these steps can help diagnose and resolve the problem. If the issue persists after troubleshooting, consider consulting a certified Toyota technician for further assistance.