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Discussion Starter · #1 ·
Hello All,
I’d like to share my traumatic experience with my 2015 with less than 18k, Ashen grey on the outside and black interior with shiny chrome wheels. It’s well equipped with leather, Nav, Bose Audio and backup camera.
On May 13th, approx. 11:10am, clear and sunny 75F Redondo Beach, CA. I entered the Volt to back out down a downward sloping driveway. I powered my Volt up with foot on brake proceeded to shift the Volt in “R”. As soon as I released pressure on the brake pedal I started to move down the driveway and picking up speed. I applied pressure to the brake pedal and my Volt continued picking up speed and would not stop. I continued to apply the brakes and the volt continued and crossed the street and impacted the residence directly across to finally stop my volt. The brakes felt extremely mushy extending about ¾ to the floor but not completely to the floor. When this occurred, I was in battery mode but the engine was engaged and running at high RPM and heard by me and a passerby while the volt was moving. I called AAA to pull me out. I was stuck on the tree and front steps. I called in the incident to my insurance company so I could start the claim and have a claim #. Police arrived 40 minutes later to take a report and give me a field sobriety test. That was a little embarrassing but glad it was done. Now it’s documented that I was totally sober. I’ve read 1-or 2 threads regarding non-operating mushy brakes but nothing about a volt in R coming down a slope and not being able to stop. I called On-Star to see if they have a log of codes generated from my Volt within the last 24 hrs and was told no. I am VERY grateful that I did not hit another person, animal or vehicle while not being in control of a fast moving volt crossing sidewalks and a residential street.
I’m looking for suggestions on next steps and possible causes. Should I take it to an independent auto body repair shop or Chevy dealer who does body work. Talk to an attorney? Call GM? Known issues? I work as a courier and have not had an “at fault” accident in over 25 yrs and know how to operate motor vehicles.

Any thoughts are greatly appreciated. I wouldn't want this to happen to another Volt owner!
 

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No codes - floor mat under the brake pedal? That doesn't explain the fast-running engine in battery mode, though.
 

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Hindsight is always 20/20, but reaching for the emergency brake would have been something to try, but agreed, it's not intuitive like an e-brake pedal or lever.

Why the engine was running is a mystery. Sometimes unintended acceleration is caused by the driver hitting the wrong pedal, but the mushiness of the brakes seems to indicate you were using the brakes.

I've had a couple of instances in the volt where the car does strange things to cause my heart to jump. One was when I pulled into the garage, stopped the car, got out, realized the rear end was sticking out of the garage, so I hopped back in, started Dan quickly shifted to D, and the car moved forwards where hitting the brakes mushed to the floor causing that signing feeling in your our gut. This one is explained by the power brake pump not quite getting enough pressure to stop the car - I was shifting too quickly.

The second type of incident is when I'm driving downhill on a gravel drive, tap the brakes, the front wheels start to slide, and regen gives up, causing my to lurch forward before the brakes actually end up stopping the car. I'm wondering if it's possible to do this while in R. A similar situation occurs when I'm driving at speed, a light turns yellow, I brake normally, but hit a bump causing the tires to go airborne for a split second, then the regen quits. The immediate fix was to change from very worn tires to brand new ones, but also not driving like Jeff Gordon and more like a grandpa helps avoid this.
 

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You did not say if you took the car out of R during your experience.

There should have been mechanical brakes, though you really have to jam on them. How much brakes I don't know because it's never happened to me.

The picking up speed thing is troubling. If the shifter was in N or D even more troubling.
 

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No license plate on the car, so you just bought the car? Are you a left foot brake pedal person? Brake pedal and accelerator pedal pushed at the same time? Floor mat caught the accelerator pedal? Something physically preventing full pressure on the brake pedal?
 

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I wonder if the "black box" will reveal anything?
 

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Emergency brakes are there for this exact type of scenario. One of the first things people should do when they buy a new car is familiarize themselves with their operation.

As for the lack of power assisted brakes, brakes DO still work without the booster but you need to really mash the pedal.
 

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Ouch! Glad everyone is ok at least. I'd recommend taking it to a GM dealer first. Have them estimate the body work and inspect the braking system. Perhaps the sound you and the passerby thought was the engine was actually the brake booster running dry.

I don't know how much time you had between realizing the brakes were gone and hitting the home. But definitely jump on that Emergnency/Parking brake if you ever find yourself rolling without brakes. Squealing your tires and maybe wearing out your pads is much preferable to a collision.
 

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I'm guessing that you're? at least 50 years old based on you being a courrier for 25 years. You're driving a new to you and still somewhat unfamiliar vehicle you've only owned for a few weeks. It started out as a low speed maneuver where you would have been working the brake to modulate your speed as you reversed. This event has all the classic details you'd expect to hear when someone hits the wrong pedal.

I'd have the brakes inspected by a mechanic to rule out the unlikely possibility of a total failure there. But barring that the most plausable explanation is you hit the wrong pedal. It happens every day and it could happen to anyone.

Best advice I've ever heard to deal with "sudden acceleration" in a car. Take your foot completely off of the "brake" and then firmly apply the brake.
 

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That was a pretty hard hit. Sounds like driver error, but, we need to see what GM says.

Does this car have any mods to the electrical systems such as fog lights or radio amp? Improper grounds can cause intermittent brake booster disconnect.
 

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Discussion Starter · #16 ·
Thanks for the input everyone. I really appreciate it.In the short amount of time I really didn't think much about the emergency brake since it is button/switch not really in line of sight. I traveled no more that 40 yards Though possible, I highly doubt I hit the wrong pedal. For that to happen I would have to release the brake pedal after shifting into R after my volt started rolling/accelerating then move my foot to the accelerator. If that was the case I would think I would notice a more pulling sensation of the drive kicking in. The way I back out in reverse is slowly release the brake pedal and establish backup speed. Since on a downward descent there would be no need for acceleration until I leveled out at best. Anyway, I have a damaged Volt that needs to be repaired. I'd really like for the brakes to be inspected for possible issues. Very rarely have I had to back down a downward sloping driveway in any vehicle and this was the first time for me in a volt. The last thing I expected was my volt or myself to have such a difficult outcome to a fairly simple maneuver.
 

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If the brakes did not make pressure, it sets dash lights, the ABS/BRAKE light, SC/TC light, (and CEL?) since it affects SC and TC. If the brakes made pressure, the brake pedal will stop the Volt at WOT. It's got mechanical backup. ie - with no battery in the car at all, the brakes work.

It will be interesting to see what the outcome is. However, unintended acceleration is an extremely common complaint with all brands of cars. Tesla has a kill switch in the brake circuit (hit brake, no motor) and somebody recently mowed down a couple of parked cars when the driver reported unintended forward acceleration, which is technically impossible if the brake is used.
 

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Are you positive it was the engine running, and not the AC compressor and radiator fans?

Wasn't there a service bulletin out for some Volts that had issues with the antilock module locking all fours brakes out so the pedal felt hard but no braking happened?

I seem remember reading that a poor choice of ground locations for an aftermarket headlight mod produced that effect, too, presumably by backfeeding the brake module.
 

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