Electric "buzzing" sound

Welcome to our forum anapurano. Please provide some additional information: does this occur after having driven your car or even when the car has not been driven recently (and the engine is totally cold)? Does it occur after you lock the car? What are the environmental conditions, that is, do you live in a humid climate and have been using your AC (water that has been condensed will continue to drip onto the exhaust after shut down)?

Thanks for the interest, JS. The engine was hot. I had just returned from a 2 hour drive. The air temperature was 60-70. The vehicle was unlocked. The fob was in the cup holder. I was running the air on the drive. I had a Trailblazer SS that would burn off condensate on the exhaust after a drive. This sound, in my estimation, was completely different. I believe it had a rhythm. In that, I mean that the condensate on my SS would drip and burn off at different intervals. This sound was more calculated so I think it may have been something different.

I have noticed what I think is similar to what you described. When I park in the garage after a ride and step out I will hear electronic type buzzing of what I expect to be systems shutting down. Even as I lock the doors and walk away I can hear it. Always did it so it doesn't concern me as it doesn't sound like a noise of something broken or wearing to me. Also, I still notice the backlight on the center display so that confirms some things are still active and shutting down.

Hope this helps ease your mind. Enjoy the ride!?

Are your headlights on? Might be the HID ballast... Just a guess...

What wavridr100 said. It takes about two minutes for all the systems to shut down in sequence. I had one heck of a time tracking down a current draw issue on a 2005 Duramax and that's what we found was happening. One of the control modules weren't shutting down and you could hear it buzzing. We had to use an amp probe to finally figure it out and this is when I got educated on how the individual control modules shut down on newer GM vehicles. If you still hear it after two minutes then I would dig deeper to find out what's going on.

We have seen several "issues" diagnosed as bad or failing control modules, so the control module theory as the source of the noise makes a lot of sense.

anapurano said:

Thanks for all the feedback. The headlights are/were off. This is my first "hi-tech" car so I thought I'd ask to ease my anxiety. Just finished a first pass through Topanga Canyon this weekend. Needless to say, I'm enjoying the ride View attachment 19508

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Wow! Awesome loop!

Both my 14 and 15 do it so I believe it is normal. Just sit in the car for a couple of minutes after turning it off and you will hear it clearly.

Bob / anyone else; If this noise lasts after the car is turned off, can its source be identified, and its location be nailed down? Is so, can its location be photographed?

There is a engine coolant temp override for fan when car is turned off

When the buzzing is heard look to see what the water temp was and look to see if fan is on as it maybe the override is on
and if so that is normal, it might be the relay for this

Same buzzing sound on my Chevy Cruze, so I hit the lock button and it goes off within 30 seconds, unless, additonally, it is the electric fan J.R. has mentioned.

Thanks everyone for the overwhelming replies and information.

Does it sound anything like this?

Finally got back to Tuna Canyon with a card in the PDR. Second run, this time with a brave passenger.

My car does the same thing. I'm certIn it has something to do with the climate control system. I was able to make it stop by turning off the AC before stopping the engine. My would go off for hours until i figured it out.

J.R said:

There is a engine coolant temp override for fan when car is turned off

When the buzzing is heard look to see what the water temp was and look to see if fan is on as it maybe the override is on
and if so that is normal, it might be the relay for this

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JR where is the override located? I have not learned al the buttons by a long shot and need this one in my quiver.
So far no issues but have no mies on my 2015 at all, weather too funky for me to trust the tires yet

Oldfalguy said:

JR where is the override located? I have not learned al the buttons by a long shot and need this one in my quiver.
So far no issues but have no mies on my 2015 at all, weather too funky for me to trust the tires yet

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Fan run on is controlled by the PCM calibration
Here is what the stock settings are shown below and could be adjusted via a tune

What is being done in stock tune is if shutting engine off and coolant temp is above 217 degrees PCM could command for up to
18 mins the fan and it's relay being on to bring the temp down

Remember when engine is first turned off the engine bay temps will go even higher so the run on will force the temps lower with the fan on and as long as the battery voltage is high enough