High Pitched Ringing Noise in Cab

Hello, this is my first post because I can’t seem to find anything on this. Today my truck (99 Prerunner) started making this high pitched ringing noise, seemingly coming from inside the cab. The noise is constant and won’t stop even when the truck is off and the battery is disconnected. Anyone have any ideas or have ran into the same issue? The noise is very annoying and I have a four hour drive coming up which will drive me to insanity. Thank you to anyone who has any information!

 

Get earplugs so you can root around in there. Must have its own power source or magic. I don't think you should drive if you cannot hear or focus on the sounds of traffic and your tires.

 

Find what's been lost under the seat and remove it.

Or wait long enough and it's battery power source will die.

Your description indicates that there is no way it's a truck problem.

 

Try throwing away the CD you have in the player.

:-D

Seriously, welcome to TW and what else have you tried to locate the source? If it's actually part of the truck it would be some power-always-on device, like a capacitor or something.

 

There’s absolutely nothing with its own power source, everything in the truck is connected to the battery and doesn’t run off its own power. (Speakers and hideaway sub) I even tore the speaker out of the wall to see if there’s something behind it, and nothing. I’ve cleaned out the truck and there’s nothing but high pitched ringing. Am I just going crazy?

 

Did you disconnect the 12 volt battery in the truck?

 

Yes.

 

I may be speaking out of turn because I don't know of any within the truck, just thinking outside the box. Understand an electrolytic capacitor. It connects across the + and - poles of a circuit and stores electricity (which is why they are so dangerous in high voltage circuits, like old television sets.) They are generally used to control line noise and unexpected spikes. When you disconnect power, these still retain electricity. They can possibly exist in audio equipment such as amplifiers, etc. When I have heard "ringing noises" it's always been (for me) a relay or an induction coil emitting the sound. I saw you disconnected the battery, but something has to be driving this sound. Is there possibly leftover remnants of a security system?

So in your investigation there is no way to tell where it's coming from, doesn't get louder or quieter when you crawl around? Speaking of outside the box, it may sound like it's inside the cab, have you rolled under the truck and can you hear it from there?

Possibly, but I would open a new thread to diagnose that one.

 

Odds are trending that way......

 

@PrerunnerSam Did you find the source? Inquiring minds want to know.

 

Never to return.........

 

Well I know if it were me . . . I might have found it and it was something dumb I did and be too embarrassed to reveal it. Like this guy LOL