Triangular Warning problem- Please help me

Did you open the door while the car was running? H

 

Check your 12V battery out-put in the morning with a multi meter on 12v. You want to see 12.6 but not lower than 12V. It may be time for a new 12v battery? H

 

You may want to check the coolant level in both the overflow bottle and the radiator. If the temp indicator light is on, chances are the ICE is overheating. That is not a good thing on these aluminum engines.

You can buy a digital multimeter at Radio Shack, WalMart, and many other places. They are not real expensive unless you buy a top of the line one.

You can also check the voltage with the Prius. Run the test that is in the following link and post back all three voltages you see in the test. Run the test after the Prius has set overnight or for at least eight hours.

Weird stuff happening? MPGs dropping? Test The Battery | PriusChat

 

Also, check the engine oil level on the dipstick.

 

First of all how many miles? If it's a cooling problem you need to check the coolant level in the radiator when it's cool. Have to remove the radiator support opening cover over the radiator to get to the radiator cap (Picture attached). Only remove radiator cap when engine is cool. Engine coolant reservoir (in front).
Second Check the inverter coolant reservoir (IMG_1710 near the back) with the cap off and the ignition on. There should be good flow in the reservoir. If not, the inverter water pump may be bad. There is a T-SB recall on that (free replacement).
If coolant in either reservoir is low, are low add Toyota Super Long-Life Coolant.
Also check to make sure the v-belt hasn't broken.
Check to see if there is any buildup of "pink crust" on the water pump, indicating leaking. (picture attached). If so, the coolant level in your radiator is probably low too and engine water pump needs to be replaced.

 

Harbor Freight sells some very inexpensive multimeters (like under $10).