On a four-lane highway, I was in the right lane and moved into the left lane, accelerating under full throttle to pass a car. After passing it, I moved back to the right lane and when I released the gas pedal, the car kept going - it just kept accelerating! I pressed and depressed the full range of the pedal to make sure that it was free to operate, but that didn’t make any change. At wide open throttle, it was stuck. As hard as I could, I then put full pressure on the brake to try to slow the car down as it was continuing to accelerate. I could tell brake failure was imminent because they were getting hot. I shifted the transmission selector up to Neutral. After the engine momentarily overran to the rev limiter, it then settled to 4000 rpm. While it was in Neutral, I continued to press on the brakes to stop. It did stop and after 30 seconds the engine slowed to a normal level of idle. The throttle seemed to respond normally. After shifting to Drive, I headed to the dealership. Around 30 seconds after starting to the dealership, the “grade braking on” appeared and then went off. It was a flat road and I was going 20 mph and not pressing on the brake pedal. The tow/haul mode was not on. Before I agree to what the dealership finds, would you please diagnose all of this and give me your advice? Thanks.
Hey there. From your description, it sounds like the throttle body became stuck. Since this vehicle does not have a throttle cable, it is possible that a sensor malfunctioned and caused the throttle to stay on. These vehicles have been known to break the gears inside the throttle body and cause the symptoms you described. It is possible that the throttle body may need to be cleaned or replaced. Also, in the future, if the throttle sticks, the best course of action is to simply turn the ignition off. Don't turn it all the way back, because that would lock the steering wheel. Only turn it back one position to the accessory position. If you would like to have a professional outside of the dealership inspect the stuck throttle, a certified technician from YourMechanic can come to your car's location to give your Chevy a look.
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