2010 Toyota Highlander Owners Manual - Page 558

5-2. Steps to take in an emergency If your vehicle overheats The following may indicate that your vehicle is overheating: ● The needle of the engine coolant temperature gauge enters the red zone: The engine may be overheating. ● "Hybrid System Overheat" is shown on the multi-information display: The power control unit may be overheating. Follow the correction procedure as described below. Correction procedures