My 2009 hybrid Tahoe accelerates uncontrollably on occasion. The issue arrises commonly in stop-and-go traffic when the hybrid system starts/stops the gasoline engine regularly. I notice in many circumstances when switching gas/electric modes the vehicle lurches forward. The feeling is the same as letting out the clutch quickly on a vehicle with a manual transmission. I have done as much research as I can and it appears the problem points to issues with the transmission fluid pump(s) and/or control modules. When the system operates on the gas engine, the hybrid Tahoe's transmission relies on an engine driven hydraulic fluid pump. When the system switches to electric mode, an auxiliary transmission fluid pump turns on, driven by an independent electric motor. The lurch I described results from what I believe to be a failing pump or control module, or a combination of the both which engages gears when it shouldn't. this lurch is rather dangerous as I have had to jump on the brakes many times to avoid rear ending other drivers. I have spoken with several individuals who own, drive or have driven these gmt900 series hybrids (2008-2013 Chevy Tahoe/Silverado hybrids, GMC Yukon hybrids, Cadillac escalade hybrids) all individuals have described the dreaded lurch. Some say replacing the electric auxiliary transmission fluid pump solves the problem, others still have lurching issues. One individual who drives a Cadillac escalade hybrid claimed to have actually rear ended someone due to the uncontrollable lurch. As for my personal car, the lurch occurs in stop and go traffic and occurs at least once a week, sometimes more. Thankfully I have not been involved in an accident yet, however I feel one may be imminent. Here is a link to a Tahoe/Yukon owners form where I have shared some of my findings: Https://www.tahoeyukonforum.com/threads/hybrid-transmission.104102/

- San Antonio, TX, USA

I have never had any issues other than the recalls with my Tahoe. I pulled into a parking space at my bank. As I got into the space. The brakes went to the floor and I put both feet on the brake pedal at this point. The rpms went up. It was like the engine came to life by itself. It self accelerated over the concrete spacer and sidewalk into the bank's brick wall. The airbag deployed upon impact. There was never a time it decelerated. There was no one in the car but me thankfully. There were no warning lights. There were no bells warning of the failure. I would estimate it took 2-3 seconds to go from almost stopped in a parking space to hitting the brick. I am so shaken by this incident and I have no idea what to do. GMC has been informed.

- Lebanon, OR, USA