Strange 1000 Hrtz Electrical Tone After Shutting Down (1 Viewer)

[bamelanc]

Turned key off and immediately heard this tone. This is the second time I’ve noticed it. Same pitch both times. Duration was similar. Had enough time to get phone out and select voice recorder and catch almost 30 seconds of audio. The tone/whistle is a straight up B at 1000 hrtz.

I’ve heard similar sounds like this from old power amplifiers are they power off. Maybe a bad capacitor/resistor/transistor?

I can’t upload the audio or video of the screen recording.

 

[fyton2v]

Is this one of those “wanna know how to keep a moron in suspense” gags?

 

[1969FJ]

Can you at least focus on the source of emission.

 

[Grayscale]

If I charge my phone and use it as a radio, I can hear the ignition when the distributor is spinning. If I count it out really fast, I can figure out which plug is misfiring / needs cleaning, lol.

A bad evap system causes a trombone/ Doppler effect when I park in the sun (the tank is in a hot cab which is really unique in the auto world) during the summer. I think that mud daubers basically caused my evap system to be a bit pressurized and do this whole whoopie cushion thing - strange. When it is really cold, on my beater pickup, the evap system opening sounds like a loud, high-pitched, whistle, first time was kinda scary.

 

[Pura Vida]

Hmm. I heard a similar noise from my HJ45 but figured it was normal

 

[fyton2v]

I kinda want to hear the noise. On the off chance you don’t know how to post it somewhere that can be heard, send me a personal message. I’ll give you my email and I’ll post it for you.

 

[B y r o n]

Is it possible the sound you are hearing is the pressure equalizing in the gas tank? If the tank/fuel system isn't venting properly a vacuum is created in the tank. You won't necessarily hear the noise with the engine running but once you shut it off it will be the only sound.

 

[Steamer]

Could it be vacuum equalizing somewhere? My rig would do that now and then when I ran a carb and it seemed to come from the carb area. I never identified it and with the Sniper, it never happened again. I Googled up a 1000 hertz tone to get an idea of your description.

 

[bamelanc]

I haven’t ran it since Friday evening and I heard it again this morning after turning on the running lights while changing out the headlights.

 

[bamelanc]

I kinda want to hear the noise. On the off chance you don’t know how to post it somewhere that can be heard, send me a personal message. I’ll give you my email and I’ll post it for you.

I’ll send you the audio file. PM me your email.

 

[bamelanc]

Is this one of those “wanna know how to keep a moron in suspense” gags?

Not today. Not saying I’m above that though…

 

[bamelanc]

Could it be vacuum equalizing somewhere? My rig would do that now and then when I ran a carb and it seemed to come from the carb area. I never identified it and with the Sniper, it never happened again. I Googled up a 1000 hertz tone to get an idea of your I w

Can you at least focus on the source of emission.

I actually heard it outside the cab this morning. Definitely louder in the cab.

 

[bamelanc]

Could it be vacuum equalizing somewhere? My rig would do that now and then when I ran a carb and it seemed to come from the carb area. I never identified it and with the Sniper, it never happened again. I Googled up a 1000 hertz tone to get an idea of your description.

Not saying it can’t be, but I think it’s not a mechanical/hydraulic cause I think the tone would change as forces equalized. The only change I hear is volume, gets louder and softer, pitch is the same.

 

[B y r o n]

An easy check to see if it is in the tank/fuel system is to crack the gas cap so it is not on tight. Run the vehicle and when you shut if off see if the noise is still there. If not you have the source for the noise.

 

[middlecalf]

I haven’t ran it since Friday evening and I heard it again this morning after turning on the running lights while changing out the headlights.

Was this without the motor running or having just run? If so, then nothing to do with vacuum, but electrical. If not, then what @B y r o n says.

 

[bamelanc]

Was this without the motor running or having just run? If so, then nothing to do with vacuum, but electrical. If not, then what @B y r o n says.

Engine has not been ran since Friday. I'm pretty sure it's electrical. No speakers in the vehicle.

 

[bamelanc]

Engine running, you can see the 1k peak, engine off, you can see it. Dies a minute or so after the key is turned off.

 

[B y r o n]

Do you have an electronic fuel pump?

 

[bamelanc]

Believe it’s OEM. So I don’t believe so.

 

[wimberosa]

shot in the dark....perhaps unplug the carb cooler at the motor pig-tail to see if its that?