Pull off the road carefully, stop the vehicle and turn on the emergency flashers. Set the transmission to position "P" (automatic transmission) or neutral (manual transmission) and apply the parking brake. Turn off the air conditioner if it is in use.
If coolant or vapor evaporates from the radiator or tank, stop the engine. Wait for evaporation to stop before opening the hood. If the coolant does not boil or evaporate, leave the engine running and make sure the electric cooling fan is running. If not, then turn off the ignition.
Warning! Do not attempt to remove the radiator cap when the engine and radiator are hot. Serious injury can be caused by pressurized hot fluid and steam.
After the engine coolant temperature drops to normal, check the coolant level in the tank again. If necessary, refill it halfway. A severe decrease in coolant indicates a leak in the system. Need to check as soon as possible.