[Blue Wyvern]

Ok, So, I've had this car for, about 7 months and 15K miles, and I notice that the parking brake applies when it thinks it needs to when parked ok- cool.

Now, I noticed sometimes when parking it makes a God awful buzz/crunch (ABS module application?) and then applies the (P) brake, at first, maybe once a week.

More recently it seems to have metamorphisized into it's own unholy entity- it happens more frequently, sometimes on flat ground, and worse yet, sometimes I park, (P brake not applied) on even ground, come back hours later and open the door for the car to loudly crunch and apply the parking brake- not cool half asleep getting into the car to go to work.

So I'm an Auto/machine tech, but I am stumped as to why this happens- I only drive in L mode, and firmly press and hold the brake when I park- there is no reason why this should be happening.

I imagine the logic is ( Park button pressed? Door ajar? Brake pedal pressed? wheel movement? G-force sensor status? gradation sensor status? ) any of these with a false flag except for door ajar which would probably be "true" should cause the car to panic and apply the brakes and parking brake.

Anyone noticed this?

Also any one else have a noisy/loose window regulator?

 

[Dimitrij]

I did notice sometimes parking brake makes semi-horrible noises, but I'd never had a car with an electric brake before, so I didn't know what to expect.

 

[drdiesel1]

You're putting the car into park without it being stopped.

 

[xylhim]

You could try checking out this topic for discussion on how the parking break works on the Bolt: https://www.chevybolt.org/forum/10-...ssing-park-while-still-rolling-forward-3.html

Also check out the Weber Automotive video on the teardown on the Bolt EV motor:

To summarize this information, it appears that a parking prawl is attempting to set into the transmission. If putting the car into park, and the transmission gears are still turning, the prawl will still attempt to insert itself into one of the gears to stop the movement of the drivetrain. This causes the horrible grinding sound that you hear. It sounds like people have gotten around this by slowing down, engaging the e-brake, and then putting it into park. I guess this just ensures that there is absolutely no movement in the transmission before that parking prawl comes down.


This is just my interpretation of whats going on, I could be off in my descriptions. Automotive experts, please chime in and correct me if I'm wrong!

 

[RichCapeCod]

You're putting the car into park without it being stopped.

+1 When I first got our Bolt it did the same "crunch" noise thing. I learned (from this forum) to make sure the car was stopped prior to putting it in Park. I simply step on my brake, then hit the Park button. Problem solved.


Rich

 

[Sean Nelson]

You could try checking out this topic for discussion on how the parking break works on the Bolt: https://www.chevybolt.org/forum/10-...ssing-park-while-still-rolling-forward-3.html

Also check out the Weber Automotive video on the teardown on the Bolt EV motor: https://www.youtube.com/watch?v=APhRPSdmdmk&list=PLIn3FrDiB1lzjfZvamYdxYo9uczD2JnTT&index=1

To be very clear, the "Parking Brake" and the "Parking Pawl" are two very different things. The "Parking Brake" is what engages when you lift the little brake lever switch beside the shifter. The "Parking Pawl" is what engages when you press the "P" button on the shifter. It's best to have your foot firmly on the brake pedal while operating either one, IMHO.

 

[Blue Wyvern]

It does it dead stopped, I have repaired transmissions due to people slamming it into park before, so having the car completely stopped is a habit of mine- I keep my foot firmly on the brake until it's done setting the P brake and after I hear the pawl click into place.

The trans-axle is a solid unit on this car, if the wheels don't spin, the transmission can't move.

It has to be the ABS system, but why? and like I said, I've opened the door to my shut down, parked car with the parking brake on and it buzzes, and once before it buzzed and then set the parking brake.

 

[drdiesel1]

Are you opening the door before being stopped ?
Is the car already in park when you hear the noise.
This is an electric parking brake and the motor applies the park brake.

Is that what you are hearing ?

Stop the car. Put it in Park. Turn the key/button off.
Hold you foot on the brake pedal and activate the parking brake.
Let us know if you still hear the "crunch," as you called it.

 

[XJ12]

It does it dead stopped, I have repaired transmissions due to people slamming it into park before, so having the car completely stopped is a habit of mine- I keep my foot firmly on the brake until it's done setting the P brake and after I hear the pawl click into place.

The trans-axle is a solid unit on this car, if the wheels don't spin, the transmission can't move.

It has to be the ABS system, but why? and like I said, I've opened the door to my shut down, parked car with the parking brake on and it buzzes, and once before it buzzed and then set the parking brake.

is the car on any kind of incline? if you had an incline that was right on the edge of the sensor's set point, it might not engage every time. But when you open the door, the car boots up and then the sensor thinks it needs to set the brake. maybe not. as towing the car on a car carrier can set the brake even if it's off. maybe the action of the door opening is enough to trigger the angle sensor if it's right on the ragged edge of its setpoint.

 

[drdiesel1]

is the car on any kind of incline? if you had an incline that was right on the edge of the sensor's set point, it might not engage every time. But when you open the door, the car boots up and then the sensor thinks it needs to set the brake. maybe not. as towing the car on a car carrier can set the brake even if it's off. maybe the action of the door opening is enough to trigger the angle sensor if it's right on the ragged edge of its setpoint.

The park brake is engaged by the door latch switch when opening the door. No "sensor" involved.

 

[shocker]

Learned something new about the Bolt, from the owners manual.

"The vehicle may automatically apply the EPB in some situations when the vehicle is not moving. This is normal, and is done to periodically check the correct operation of the EPB system."

 

[grommet]

On a related note here's a Reddit post with some good information about how the parking system works. https://www.reddit.com/r/BoltEV/com...with_a_cup/?utm_source=share&utm_medium=web2x

 

[Blue Wyvern]

The park brake is engaged by the door latch switch when opening the door. No "sensor" involved.

But the vehicle knows when to apply the P brake, like when I'm up a grade, before I open the door- plus the car must know the grade since it also has a incline brake hold function you can feel when you stop up a hill- the ABS holds pressure.

The occasional P-brake test makes sense but it's new, I wonder if there was an OTA update I didn't know about, but I try manually checking every month.

Did it again last night parked flat, opened door after working BZZZT REEEEEW! Sounds like a transformer or Doc. Brown's DeLorean.

And to recap, car is stopped, foot on brake, park engaged, car shut down, then the door is opened.

 

[drdiesel1]

That is the electric motor applying the parking brake. IT'S NORMAL!

 

[BrandEver]

I have this same issue. I can come back to my car that's been sitting off on flat ground, barely touch the door and the parking brake will apply itself (often crunching because there's no foot on the brake). It's even happened without touching it before (maybe because it sensed the key?) I try to remember to apply it every time I park to avoid this but it's very annoying.