Electrical Problem: Noise from inside of Intake Manifold?...

[ajbremer]

My battery wore down after my Festiva sat for a few days and I didn't know why. Then I
began to drive it around again after replacing the steering column and in the quit of the night,
when the car had been off for hours, I went out to look in the engine bay to figure out where
the parking light relay was and I heard a hum.

At first I thought it was a fan inside or something but it's coming from inside of the intake manifold.
What I mean by that is that big aluminum casting on top and behind the engine. I noticed a large black
electrical unit and thought that it was causing the noise.

Anyway, something is running under my hood and I can't figure it out...a pump or fan or what??? Anyway,
the thing is on all the time, even with the key out. Looks like I have some messed up wiring or something.

Help???

[FestYboy]

Year and model please.

[Greywolf]

Try pulling fuzes one at a time until the hum goes away. That's the simple simon method of isolating the circuit.

If all of the fuzes are pulled and the hum is still there its an always hot, non-fuzed circuit.

This is the fastest way I know to isolate it down to a general area, be alert also to added on wires from a prior owner.

HOT suspects are usually shorted out cigar lighters, and dashboard clocks that don't work anymore. Those should be disconnected from power as soon as a drain is found.

Some twelve volt drains that are normal but low current are the radio memory, and also the keep alive power for the EEC/PCU/PCM. Those will always pull 12V, but at a low current level.

You have an advantage here, because you can hear a humming noise. A mechanics stethoscope can run that down in minutes if you have one, or can borrow one. They don't cost much and can be a valuable tool for many things.


AS AN INTERIM measure - disconnect the negative cable at the battery to save the charge until you or a friend have the tools to run it down to the source.

[bhearts]

The only thing electrical on the intake manifold is the idle air controller. If maybe a bad connector could cause it to oscillate.

Sent from my SM-G900V using Tapatalk

[Greywolf]

If it was gone bad, could it make a humming noise (1) and (2) where is it located so that it could be disconnected to check it?

I still like the idea of a mechanics stethoscope (I think of them as "STEALTHOSCOPES") to find the source of the noise. They cost around ten bucks, and can be life savers. They are the only way you can find a SPECIFIC noise in an engine bay FULL of noises