2005 GMC Sierra: sudden loss of power

Filed Oct 15, 2015 · Fuel system, Transmission · 78,480 miles · NY

Issues with emissions switch. Check engine light will not go off. Also 3 and 4th gear are completely gone out. I do not tow or have had anything even remotely heavy in this truck. It's a 2005 gmc sierra with only 78,480 miles on it. I am not the only one having issues with this 4 speed transmission. It is not heavy duty enough for this size truck. Gm needs to recall all of these transmissions. When it first started slipping I lost all power going down the road at about 55mph. The vehicle that was behind me slammed on his brakes to avoid hitting me. This problem with the transmission is going to kill someone.

Filed Aug 12, 2015 · Engine · 270,000 miles · KY

Tl* the contact owns a 2005 gmc sierra. While driving at approximately 60 MPH, the engine suddenly increased in speed to approximately 10 MPH. The contact stated that the display panel read "reduced power mode" and the check engine warning light illuminated. The vehicle was restarted, but the failure recurred multiple times. The vehicle was driven to an independent mechanic where it was diagnosed that the throttle body needed to be replaced. The vehicle was repaired; however, the failure recurred without warning. The vehicle was then taken to a dealer where the throttle body wire harness, the throttle accelerator control module, and the accelerator pedal assembly were repaired. The repair failed to remedy the failure. The failure mileage was approximately 270,000.

Filed Aug 18, 2014 · Acceleration · 195,000 miles · LA

At any rate of speed truck will go into reduced engine power must pull over out of traffic and kill engine wait a couple of minutes and then restart sometimes you can go 1 mile till happens again sometimes 50 miles very dangerous situation in heavy traffic.

Filed May 24, 2014 · Engine · 59,640 miles · LA

Crank vehicle turn corner , message engine power reduced, check engine light appeared, turn around return 200 feet to home, check all fluids connections turn off ignition, unable to start engine, let sit, unable to start engine, drive wife to work other vehicle, recheck all fluids connections, refill coolant, crank engine, coolant discharge on overflow line on cold engine, kill engine would not start, go to autozone get extra coolant and new gas cap. Return coolant level ok. Install new gas cap, engine hard to crank like vapor lock or no fuel to engine. Crank engine, let run, kill engine. Unable to crank, return to work, return in 3 hours, reinstall old gas cap, check fluid levels, ok. Crank engine let run for 5 minutes, check engine light still on, wait one hour, crank engine back to normal check engine light off, engine run ok, drive short test drive. Unable to operate vehicle safely for 6-8 hour period, unsure if vapor lock, bad fuel, fuel filter, bad plugs, coil on plugs, loose plug wire, etc. Never had any engine problems in the past. Only instrument panel cluster failure, and steering click knock that was fixed by dealer. Research problem on internet, it appears this is a throttle position sensor failure that gmc has identified as a safety problem and made a special extended coverage for 2008 to current year vehicles or ten years or 120000 miles. Fromresearch on computer, it appears tens of thousands of comments regarding this loss of power and engine stop. I am older man and reacted with caution and was near my home. Had I been on a busy street or highway a crash or injury would most certainly occurred with this disabled vehicle the cause. I had never imagined this would happen to me nor had I heard of it from any media source or dealer memos. I am hesitant to drive any distance or on certain high traffic roads due to this problem recurring.

Filed Jan 23, 2007 · Brakes, Electrical · 34,000 miles · CA

Tl* - the contact owns a 2005 gmc sierra hybrid truck. Two weeks ago while driving at 5 MPH the vehicle's steering wheel and the brakes locked. The contact was able to drift to a stop. The vehicle also vibrated, and made a whistling sound. After several attempts the contact was able to restart the vehicle. The vehicle's lost power at red lights; however, it restarted. The dealer stated that they did not have the parts to repair the vehicle, they were also waiting for a technician to diagnose the vehicle. The vehicle has been at the dealere for three weeks. The dealer also stated they didn't know where the parts were coming from, yet they've ordered the parts. The contact was currently renting a vehicle. There were no warning indicator lights present at the time of the incident. Two weeks prior to the failure, the contact's vehicle overheated and the warning indicator light appeared. The dealer replaced the water pump. The contact also spoke to gm and was told they would investigate the dealer. The contact thought there was a failure with the battery, it was defective and serviced under the warranty.

Filed Jan 9, 2006 · Engine, Transmission · 500 miles · CO

Extreme overheating of 3500 duramax while towing. Loss of power and overheating of transmission and engine. Numerous contacts with general motors and attorney general in michigan. Gm acknowledges there is a problem but don't know what the problem is therefore no fix for the problem. Are continuing to find a fix. We tow a 5th wheel in the colo. Mountains and this could lead to very serious problems if the engine should blow and we would have loss of steering and braking.