Strange Sound

[gpsman]

Only on day 4 of ownership- and loving every moment.

I live on a pretty steep road. Often I have to park on the street facing up.

Today I pulled in with the selector in L position.
The car came to a stop on the steep hill in a smooth and predictable manner. But usually I think the regen in L is too strong so I feather the go pedal a bit to reduce regen.

So I stop on the hill (facing up) and subconsiously keep my foot on the go pedal. I never touched the brake pedal. The car is stationary and silent for several seconds. My foot is still on the go pedal a little bit.

I push the park button, then hear a loud, startling grinding sound that lasts about 2 seconds.

Hmmm... that sounded really bad.....
Then I realized my foot was still on the go pedal even though I wasn't moving.

I put it in R and go back 10 yards then back to D and forward 10 yards. I tried to replicate the sound but it did not do it the second time.

Ideas?

 

[IMAdolt]

I don't know the in/out of the motor but it's basically a motor built into a gear reduction box and I'm assuming the park is a gear that sort of slides in an locks it up, now the motor could have been spinning slightly perhaps but not noticeably overcoming the gravity of your hill, maybe so slow it's not triggering whatever motion sensor it has to keep someone from engaging the park gear in motion. so it was likely the park gear trying to slid into place till it popped in and stopped grinding.

Gear and syncro teeth or made of pretty tough stuff and I got to assume these ones are no different and can probably take a little **** kicking so long as you don't do it too often, maybe in the future put your foot on the brake, I'm surprised you can put it in park without the brake engaged,. I haven't got mine yet, that's all complete guess work.

 

[gpsman]

There is no clutch (as far as I know) so I don't think the motor can move at all without the wheels moving.

I was thinking about that parking pawl thingy.

It is possible that the whole car was moving super slow. But I mean really slow like 1mm per second.

Most cars - generally tolorate shifing into park at 1 or 2 mph (1.5 to 3 feet per second).

 

[EldRick]

The appropriate procedure is to Always set the parking brake before putting the tranny in park, for all cars.
If you just put it in Park, you risk jamming the pawl in there when it is the only thing holding the car from rolling downhill.

 

[Fulmine]

After coming down a steep hill in Low, I stopped needing to use the brakes. After stopping, I felt something that led me believe the guy behind me bumped me slightly. I declined to make an issue with the guy and drove off. The next day, it happened again, except no one was close enough to bump me. Any ideas out there?

 

[DucRider]

After coming down a steep hill in Low, I stopped needing to use the brakes. After stopping, I felt something that led me believe the guy behind me bumped me slightly. I declined to make an issue with the guy and drove off. The next day, it happened again, except no one was close enough to bump me. Any ideas out there?

Not uncommon on EV's to feel a little "surge" as the car transitions from regen + hydraulic (conventional) brakes to hydraulic only. As the motor stops providing resistance, it can fell like the car surges (or is bumped).
Different EV's have different degrees of this and it can vary in intensity based on numerous factors. You may have happened upon one that is more noticeable in the Bolt's software algorithms. This is the kind of thing that could be addressed in an OTA update.

 

[bobtarlau]

I also have experienced that sound... when pushing the PARK button. It does sound alarming... and can be avoided by making sure your Bolt is completely stopped before engaging PARK. A lockout feature to prevent this from happening should have been incorporated, but it obviously wasn't. Another writer suggested engaging the electric parking break before engaging PARK. That's always a good idea!

 

[gpsman]

Ya, I know it is good to hit the parking brake first.

However, I have confirmed you CAN hit the park button and have it engage park, without your foot on the brake... and I guess even if slightly moving. Just like an older car.

While totally undesireable I'm surprised it is even possible.

 

[EldRick]

Bolt Owner's manual, p. 204

Shifting Into Park
To shift into P (Park):
1. Hold the brake pedal down and set the parking brake. See Electric Parking Brake p.210.
2. Press the button on top of the shift lever to shift into P (Park). See Electric Drive Unit p.206.
3. The P indicator on the shift lever will turn red when the vehicle is in P (Park).
4. Turn the vehicle off.

 

[ChevyCustomerCare]

Hello everyone,

The Chevrolet Bolt EV can use the Electric Park Brake, or the braking system’s hydraulic pump, to automatically apply the brakes. This creates additional vehicle security in certain situations, including a driver park request while the vehicle is in motion or on a steep hill. If anybody would like further clarification in regards to the these features in the Bolt, please send us a private message. We’re here to help!

Sincerely,

Eddie A.
Chevrolet Customer Care

 

[Pigwich]

We're actually interested in learning what exactly is causing the weird sound when we press P - I have noticed it a few times, and this morning, I was in R with the car pointed slightly nose-up-hill. I *believe* I was completely stopped. I pressed P and it growled at me!! I tried to reproduce this again, but was unable to.

If anybody would like further clarification in regards to the these features in the Bolt,

Any thoughts?

 

[dandrewk]

The sound is the transmission's Parking Prawl trying to "hold" a car that is still moving, however slightly. It is not a good sound, so you need to verify that your car is completely still before hitting the "P" button. Otherwise, it may lead to an expensive repair.

Get in the habit of hitting the parking brake before apply P mode. This will eliminate the issue.

 

[flamaest]

I think chevy needs to push out an over the air update where this car cannot be put into park in less you have the brake pedal depressed. I have noticed that if you stop the car on even a slight Hill and you are still rolling ever-so-slightly and try to go into park, that growling can happen. I think Chevy is going to see a lot of people coming to dealerships with problems related to this.

All my other cars require that the parking brake be depressed before I can go back into Park.

 

[EldRick]

The Owner's Manual is very explicit that the Parking Brake should always be engaged before Park, just like every other manufacturer of automobiles.
Do the parking Brake first, and you won't create this problem for yourself - it's an Operator Error, not a problem with the car.

 

[flamaest]

It doesn't matter what the manual says, the car should not let you do this.

. In my situation I was on an incline in my driveway and the car allowed me to select Park and then automatically proceeded to try to select the parking brake by itself. The car rolled back about 2 inches and so produced a growling sound. Again, like any other manufacturer, you should have to depress the Pedal brake before being allowed to go into Park.

 

[SparkE]

Booooo to the nanny state.

I have two vehicles that definitely do not require that the brake be depressed before placing the transmission in 'Park". I have never had a problem figuring out what to do, or a problem with either vehicle.

 

[user 1034]

I'll just add this has happened to me 3 times. Each while setting in Park while my foot is on the brake and in L and on a flat surface not moving.

I think its a bit of gear grinding in the transmission. Not sure how detrimental it is as the motor is not moving. If it fails, they fix.

 

[JeffN]

The Owner's Manual is very explicit that the Parking Brake should always be engaged before Park, just like every other manufacturer of automobiles.
Do the parking Brake first, and you won't create this problem for yourself - it's an Operator Error, not a problem with the car.

The owner manual elsewhere has an example showing use of Park first and then setting the electric parking brake. I doubt that the order matters but it probably a good idea in any car to use the brake pedal when shifting to park.

 

[JeffN]

I finally experienced this noise for the first time yesterday after 3 months of driving my Bolt. It happened when I pushed the park button prematurely while the car was still moving at about 1 mph. Scary sound.... I'll try not to do that again.

 

[flamaest]

Yes, quite scary and IT SHOULD NOT be able to HAPPEN in a car which is so software controlled. The shift nob and parking break lever is 100% software.