Toyota Prius Owners Manual
If your vehicle overheatsIn case of an emergency / If your vehicle overheats
If your high coolant temperature warninglight comes on, if you experience aloss of power, or if you hear a loudknocking or pinging noise, the hybridsystem has probably overheated. Youshould follow this procedure...
1. Pull safely off the road, stop the vehicleand turn on your emergencyflashers. Push the “P” position switchand apply the parking brake. Turn offthe air conditioning if it is being used.
2. If coolant or steam is boiling out of theradiator or reservoir, stop the hybridsystem. Wait until the steam subsidesbefore opening the hood. If there is nocoolant boiling over or steam, leave thehybrid system running and make surethe electric cooling fan is operating. Ifit is not, turn the hybrid system off.
To help avoid personal injury, keepthe hood closed until there is nosteam. Escaping steam or coolant isa sign of very high pressure.
3. Look for obvious coolant leaks from theradiator, hoses, and under the vehicle.However, note that water draining fromthe air conditioning is normal if it hasbeen used.
When the hybrid system is running,keep hands and clothing away fromthe moving fan and engine drivebelts.
4. If the coolant is leaking, stop the hybridsystem immediately. Call a Toyotadealer for assistance.
5. If there are no obvious leaks, checkthe coolant reservoir. If it is dry, addcoolant to the reservoir while the hybridsystem is running. Fill it about halffull.
Do not attempt to remove the radiatorcap when the hybrid system and radiatorare hot. Serious injury couldresult from scalding hot fluid andsteam blown out under pressure.
6. After the coolant temperature hascooled to normal, again check the coolantlevel in the reservoir. If necessary,bring it up to half full again. Seriouscoolant loss indicates a leak in thesystem. You should have it checked assoon as possible at your Toyota dealer.