Favor to ask. Ignition - Toyota Nation Forum : Toyota Car and Truck Forums

friedchicken · 06-01-2011, 12:28 PM

For those who have a 2004 corolla s. Or maybe it doesn't matter. When I switch the ignition to ON position. Thats with the interior cluster lights on. Car is not running. With that still on and the hood popped open, I hear a faint whining sound in the engine bay. It goes away once I release the key out of ignition.

Can you guys go out to your car and do the same as I described and tell me if you hear it too? I just want to know if that is normal. And if you can tell me what that noise is?

You will not hear it at all when the engine is running. BTW.

TrdSpeed140 · 06-02-2011, 01:46 AM

is the engine warmed up when you do this? could be radiator cooling fan.

is your vent blower on or off? could be that

does the noise continue indefinitely or does it stop after a few seconds? could be fuel pump priming.

saskrider · 06-02-2011, 08:05 AM

2004 auto does not make any sound but 2005 manual it makes some noise only for a few seconds, like when the fuel or battery gauge is going up, very wear, this one we bought used about 100 000km - 62 500 miles, not sure what it is

friedchicken · 06-02-2011, 12:09 PM

Quote:

Originally Posted by TrdSpeed140

is the engine warmed up when you do this? could be radiator cooling fan.

is your vent blower on or off? could be that

does the noise continue indefinitely or does it stop after a few seconds? could be fuel pump priming.

The engine not warmed up. You will not hear it when you sitting in the car. OR when your outside with the hood shut.

You have to stick your head closer to the bay with the hood open. The noise is a faint whining sound. Sounds electrical. No fans are on. Vent blower off position.

I haven't left it on to hear for a long time. I took the key off ignition in about 1 minute cause I was worried. But I'll keep it on to see if it goes away. I'll let you know.

sam333 · 06-04-2011, 01:18 AM

Is it coming from your fuel rail? Its fuel moving through the system (priming/ pressurizing it for start).

invader · 06-04-2011, 01:54 AM

The noise is emmited from the alternator, by battery voltage running through the charging system. It resonates in the plastic intake manifold... It's normal.

sam333 · 06-04-2011, 08:15 PM

Went outside opened the hood and turned on the key, and could hear the whirring. I used my auto stethoscope and put it on the fuel rail ( no sound, or just very faint humming).
Put it on the intake manifold, and a loud whirring could be heard. Put the scope on the alternator( nice humming coming from the alternator) and thought thats it, the alternator is making the noise and it is resonating through the manifold like invader said). I disconnected the alternator, listened again, no sound from the alternator, but put the scope on the intake manifold again and whirring could still be heard( with and without the scope). I followed the sound as it got louder and it ended at the IAC valve( idle air control valve). I unplugged it and the sound stopped.The interesting thing is how many different sounds there are under the hood even when the engine is not running.This may or may not be what you are hearing, but I learned something.

friedchicken · 06-04-2011, 10:01 PM

Quote:

Originally Posted by sam333

Went outside opened the hood and turned on the key, and could hear the whirring. I used my auto stethoscope and put it on the fuel rail ( no sound, or just very faint humming).
Put it on the intake manifold, and a loud whirring could be heard. Put the scope on the alternator( nice humming coming from the alternator) and thought thats it, the alternator is making the noise and it is resonating through the manifold like invader said). I disconnected the alternator, listened again, no sound from the alternator, but put the scope on the intake manifold again and whirring could still be heard( with and without the scope). I followed the sound as it got louder and it ended at the IAC valve( idle air control valve). I unplugged it and the sound stopped.The interesting thing is how many different sounds there are under the hood even when the engine is not running.This may or may not be what you are hearing, but I learned something.

Hey thanks for going out of your way in doing this. Well I'm going to assume for now its normal like invader said. You have that same whirring sound as my rolla has. Thanks guys for helping me out.

sam333 · 06-04-2011, 11:21 PM

Quote:

Originally Posted by friedchicken

Hey thanks for going out of your way in doing this. Well I'm going to assume for now its normal like invader said. You have that same whirring sound as my rolla has. Thanks guys for helping me out.

Your welcome, no problem.

invader · 06-05-2011, 12:09 AM

Ahh that makes sense. I noticed the buzzing alternator wasn't singing quite like the intake manifold, and that it was humming in my cold air intake near throttle body where the the IAC is... So there's an alternator buzz and a IAC hum.