Yaris not starting, fast whirring noise

[DrivingAround]

Hello, 

I have a 2006 Yaris 1.0 VVT-i T3, it has always started first time for the last 5 years that I've owned it, but the other day, after having let it sit for a good few weeks, when I turned the ignition switch it just made a loud continuous whirring noise and won't start. It's not like the sound you hear when a Battery is going flat, it sounds as if something is turning, but maybe something else isn't engaging with it to actually put the spark to the fuel. Does this sound like starter motor failure, or would it not be doing anything if the motor was failing? I've had a look under the bonnet and can see the engine coolant level in the expansion tank is below the low line, which is a first, so obviously I'll be topping that back up to normal levels. I'm guessing this car isn't auto-detecting a low level of coolant? Any ideas appreciated thanks. Annoyingly I don't have home-start, so would like to work out whether it's something I can fix myself or if I need to get a mobile mechanic out. 

[Cyker]

Yeah my first guess would be the starter motor too.

There is a cog that is supposed to pop-out and engage with the flywheel, then spin it up when you try and start the car.

It sounds like it's gotten stuck and can't pop out, and is just spinning in-place.

The easiest thing to try is locate the starter motor and whack it with a wooden/rubber mallet a few times then try and start the car again to see if that frees the cog up.

If that doesn't work, might need to remove it and spray it with some WD40 or similar to try and free it. You should be able to move it in and out by hand while you have it out. (Don't do this on the car as you don't want to accidentally get any WD40 on the flywheel!)

If that doesn't work, may be the solenoid that makes the cog pop-out has somehow failed which usually means you need a new one unless you are good with electronics diagnostics!

[flash22]

its a weak starter solenoid (small round part on top/side of the starter) give it a few taps and see if it starts, don't rule out a dying Battery

[wildtapholer]

I was always told that if your car engine won't turn over and if the car is facing a wall, if not get someone to watch them, turn your lights on and turn the key and try to start the car, if the lights go out it's the Battery if they don't it's the starter.