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Discussion Starter · #1 ·
Hey everyone, I just bought a 2020 Bolt new with 4 miles on it.

I am hearing a high pitch noise when I accelerate around 30+ kw and regen 10+ kw. The noise mostly occurs at speeds below 30 mph. It is also present when I'm trying to creep over the small hump as I slowly enter my garage.

It goes away completely at steady speed.

It doesn't sound like the pedestrian warning system. It also does not match the whir of the motor. It's a third distinct sound. The sound can be heard if the windows are up or down and I hear mostly from the front passenger area of the car. Its pretty loud in the cab and drowns out the pedestrian warning sound and the motor whir.

It's present in D and L.

The best way I can describe it is crickets at night that increases in volume as thes harder acceleration or regen. It could be electrical interference with the radio but I can't be sure.

Is this a common/normal issue?

Sorry to start off with a concern...
 

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Discussion Starter · #3 ·
there went my theory out the window.

Welcome to the forum.
The pedestrian warning system sounds like crystal/glass howling that oscillates and changes with speed. That's the only sound it makes correct?

I actually don't mind the pedestrian sound and the normal motor whir; sounds like a car from a cheesy 80's movie :)

This noise sounds like coil whine or heavy electric current. It is clearly coming from the passenger side and seems based on power draw and regen.
 

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This noise sounds like coil whine or heavy electric current. It is clearly coming from the passenger side and seems based on power draw and regen.
My 2017 makes a very high pitched noise at the start of accelerating and at the end of deaccelerating. Only hear it if I have the radio off.
 

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Discussion Starter · #5 ·
My 2017 makes a very high pitched noise at the start of accelerating and at the end of deaccelerating. Only hear it if I have the radio off.
I can hear this over the radio and the AC; appears to be louder after having driven for a bit (~20 minutes).

It looks like this has happened before:

I'm still trying to look further; I don't see where anyone pinpointed by some cars have the sound and others don't.
 

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Discussion Starter · #6 ·
I think I narrowed the issue down to a noisy power inverter. I think I'll drive it for a bit to see if it settles down; it wasn't present 50 miles ago. Hopefully something that doesn't get worse. If so, that's what warranty is for I guess.
 

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I always heard a sound with the windows down in a drive thru lane where you have a wall next to you. It happens at very low throttle when you are first taking off. It's the inverter. It sounds like an electric drill when you just barely press the trigger. If it's that... it's normal.

Mike
 

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Discussion Starter · #8 ·
I always heard a sound with the windows down in a drive thru lane where you have a wall next to you. It happens at very low throttle when you are first taking off. It's the inverter. It sounds like an electric drill when you just barely press the trigger. If it's that... it's normal.

Mike
I hear mine with the windows up... Like it's behind the dash on the passenger side. It is louder with the windows down and at certain times it's actually louder than the pedestrian warning sound.
 

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I think I narrowed the issue down to a noisy power inverter. I think I'll drive it for a bit to see if it settles down; it wasn't present 50 miles ago. Hopefully something that doesn't get worse. If so, that's what warranty is for I guess.
Why wait? If it's already louder than a warning signal (pedestrian warning), I would take it in.
 

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Discussion Starter · #10 ·
You may be right. I need the car for the next few days so I'll try to get a good recording of the noise and take it in this Friday.
 

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I have the same.

It is kind of like humming, transformer sound. It is present when it is warm or battery/electrical is warm.
On winter I did not hear it. Only after morning charge. Then - never.

It got warmer and the noise is back...
It has been there since day 1 I had the car. I could not find out what causes it, but modulating of the accelerator causes the noise to change. It changes with load (kW), not really speed.
It has presented the most noise around 15-25 C ambient, but above that it kind of got less, if it makes sense.
 

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Discussion Starter · #12 ·
I have the same.

It is kind of like humming, transformer sound. It is present when it is warm or battery/electrical is warm.
On winter I did not hear it. Only after morning charge. Then - never.

It got warmer and the noise is back...
It has been there since day 1 I had the car. I could not find out what causes it, but modulating of the accelerator causes the noise to change. It changes with load (kW), not really speed.
It has presented the most noise around 15-25 C ambient, but above that it kind of got less, if it makes sense.
This is the exact thing happening to me. A high pitch inverter noise. I've got a video of it but haven't had a chance to upload it anywhere yet. I am going to ask the dealer service department to look at it Friday night or Saturday. If I get any answers I'll let you know.
 

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Discussion Starter · #13 ·
I took the car in this afternoon to get it quickly looked at. The service tech that rode with me believes the issue may be a noisy coolant pump that runs with load.

The tech said he'd email GM about the issue but doesn't expect a response for a couple days. In the meantime, car is good to drive.
 

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I took the car in this afternoon to get it quickly looked at. The service tech that rode with me believes the issue may be a noisy coolant pump that runs with load.
I can tell your technician that there are three coolant pumps in the Bolt. The one on the passenger side is for the heater coolant loop, and only runs with the heater. The one at the middle front is for the battery heater, and also only runs with that heater. The high power electronics coolant pump, which runs continuously at 2025 rpm whenever the car is on, is on the driver's side.

There is also a motor/gearbox pump that circulates ATF through both.

I believe you may have been right about it being motor inverter whine.
 

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I took the car in this afternoon to get it quickly looked at. The service tech that rode with me believes the issue may be a noisy coolant pump that runs with load.

The tech said he'd email GM about the issue but doesn't expect a response for a couple days. In the meantime, car is good to drive.
yeah... right....
maybe have him do an oil change and refill electrolyte (acid) in the battery

EDIT.
I take all of theirs opinion with a grain of salt.
The other day I went to get the cracked A/C hose replaced. Well, the advisors were sure it is normal condition... because the hose is bent.
I am like - oh, really. OK, I see. But just in case, please bring any of Bolts you have on the lot and let's compare.
None of the 2020's had cracks.

so, man, water pump changing its load is a load of crap.

 

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Discussion Starter · #16 ·
I am going to go through all the motions to get through this part of the service process.

One thing I noted was that it isn't 100% based on power draw. At lower speed and kw draw, the noise is consistent in pitch and volume. Once it passes a certain speed, the noise winds down despite consistent kw draw.

The service tech believed the coolant pumps ran harder on load and that was the issue. I know everyone says that's unlikely, but at least he emailed GM to get a second opinion.

I'll update the thread when I get a response from them.

Other than the noise... I'm loving the car.
 

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I am going to go through all the motions to get through this part of the service process.

One thing I noted was that it isn't 100% based on power draw. At lower speed and kw draw, the noise is consistent in pitch and volume. Once it passes a certain speed, the noise winds down despite consistent kw draw.

The service tech believed the coolant pumps ran harder on load and that was the issue. I know everyone says that's unlikely, but at least he emailed GM to get a second opinion.

I'll update the thread when I get a response from them.

Other than the noise... I'm loving the car.
It's a bit of setup if you don't already have the devices, but an ODB2 reader combined with Torque Pro (Android) and the PIDs for the Bolt will show you Battery Coolant pump speed and Electronics Coolant pump speed.
 

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Discussion Starter · #18 ·
I've got a reader (non-graphing) at work I can borrow. I'll see if I can find a correlation. Thanks for the suggestion.
 

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I've got a reader (non-graphing) at work I can borrow. I'll see if I can find a correlation. Thanks for the suggestion.
Just want to be clear. You cannot use an ordinary code reader for this. You need a Bluetooth enabled reader like this one:
34517


Then connect it to Torque Pro on an Android phone. You then need to add Telek's Bolt PIDs for Torque Pro. Then you can get the readings you are looking for.

ga2500ev
 

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Discussion Starter · #20 ·
I was able to cut out a part of a video I made and upload it to YouTube. Its very short; noise starts at 5 seconds in.


I apologize for the blinker noise -.-
 
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