The transmission control module (TCM) began acting erratic. At times the transmission will not shift but several times it has gone into park( with no warning) when slowing down causing the wheels to lock and the truck skids to a stop. I was nearly in 2 accidents when this happened. Both time I was hauling a load and caused the traffic behind me have to swerve to not run into me. In looking into the issue I found that in 2011 GM had put out a shop notice that they had a known problem with the TCM and they thought it might be caused by a non-OEM fan belt causing electrical discharge that might impact the TCM. A second shop notice from GM stated that the issue was due to heat and since they has mounted the unit on the fan shroud it should be moved. But none of the shops I went to knew about these shop notices from GM. Thousands of TCMS have failed but no recall. GM has now greatly reduced production of replacement modules and the cost of a new TCM has gone from $400 to $5000 ( Plus programing ) and a long wait time to get one. You can get one refurbished for $1200.

- Atwater, MN, USA

It is a transmission control module wear a lobster transmission into a Garin. Will not let you speed up or speed down and it is unsafe and GM IS making us pay for the bill. The contact stated transmission control module all across the country on back order, you cannot get a dealer to get you one within six months GM should have to do something about this.

- Fredonia, NY, USA

The vehicle started to shift on its own mostly between the upper gears even though terrain or load had not changed. At slower speeds the vehicle started to automatically shift into park and lock up the wheels. This caused a very serious risk of injury to me and the people behind me when it would lock up. After stopping the vehicle sometimes does not move when in drive. There are no warning lights Took it to a shop and they checked it over. I was informed that there is a known issue with the electronic transmission control unit (TCM) for the Allison Transmission. The issue is with the location of the TCM. GM has developed a new unit to replace the original TCM that is engineered to no be affected by this. But due to the demand GM has a back order on the new TCM. The cost to get a TCM has risen from $800 dollars to $5000 dollars if you can find one.

- Atwater, MN, USA

My truck has been at a dealership since May 31st, 2022. It needs a TCM. While researching, plus calling aftermarket parts suppliers(Auto zone and others), and also calling auto recycling/salvages yards, there are Zero TCM's available unless you get lucky at a auto salvage yard minutes after a wrecked truck shows up. There is a huge issue with the TCM's failing on these 10 year old trucks, and GM refuses to allow their supplier to make replacement TCM's. I have lost the use of my truck for almost 6 months at this point. I would also like to know how many other customers are waiting for a TCM.

- Essexville, MI, USA

The contact owns a 2011 Chevrolet Silverado 2500. While the vehicle was idling at a red light, the contact depressed the accelerator pedal, but the vehicle failed to accelerate. The contact had to place the gear shifter in park to restart the vehicle on several occasions. The stabilitrak and traction control indicators illuminated. The vehicle was taken to sands Chevrolet glendale (623-931-9331, 5418 grand ave, glendale, AZ 85301) where it was diagnosed that the transmission control module failed and needed to be replaced. The vehicle was repaired. The manufacturer was notified of the failure, but did not assist. The approximate failure mileage was 77,000.

- Glendale, AZ, USA

Throtle position sensor is always on even after replaced transmission is shifting, poorly, needs reprogramming gears are shifting roght malfuntion of transmission soleinoids, bad manufacture,

- Laurel, MD, USA

At 75000 starting have problems with transmission always down shifting. At 126000 torque converter came apart and caused damage to the transmission pump and bell housing. The truck was being driven in both situations.0

- Splendora, TX, USA

Transmission control module and egr valve needs replaced at 61,000 miles.

- Bonney Lake, WA, USA

The contact owns a 2011 Chevrolet Silverado. The contact stated that when adding oil to the vehicle, it was discovered that the transmission dip stick tube had separated from the vehicle. The vehicle was taken to a dealer, who diagnosed that the dip stick tube needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure. The approximate failure mileage was 70,000.

- Texarkana, AR, USA

Truck downshifts to passing gear such as entering a highway on ramp and stepping down to enter slower traffic engine revs to red line on tach because it does not shift into any gear leaving you hung out to dry in traffic until you figure out what's goin on you have fully let up for it to find a gear by this time your speed came drop 10 mph very dangerous, had to two different dealers twice both said it has no problem one said it was the torque management system and it was normal.but if I wanted it to go away take it some where and have the program wiped from computer but warranty will then be void.also truck slams into gear when slowing down to go around a corner.when starting vehicle it jumps forward so bad I am afraid to keep it in my garage. Spoke to two different Chevy reps both are like talking to a wall, they are not employed to help you just to run around in circles until you give up.research all Chevy products before buying. Silverado have alot of transmission issues. Just a horrible truck.

- Trenton, NJ, USA

2011 Chevrolet Silverado. Consumer writes in regards to mechanical, electrical and transmission problems with vehicle. The consumer stated while driving down the road on a steep incline, with the truck and trailer loaded, the engine's RPM suddenly went to 5500 RPM, without increase in acceleration. He depressed the brake to release the cruise control, and strongly pressed the gas pedal several times before the engine would return to a normal RPM.

- Magdalena, NM, USA

New vehicle front end suspension began to randomly violently shake at different speeds (once @ 55 mph & once @ 70 mph). The shaking was so bad that the driver could barley hold the wheel straight to avoid losing control & crashing. While this was happening the vehicle 4 wd light was blinking despite the fact that the vehicle was in 2 wd. Once driver was able to pull over he inspected the outside of the vehicle to find no mechanical issues (no flat tires, things in the wheels, etc...). driver then began driving again & the vehicle was fine as if nothing happened. Driver called onstar & they stated there were no fault codes in the system. Several days later the same thing happened while driving at 70 mph. This time the driver nearly got into a roll over accident. He was able to get the vehicle to the side of the road. Upon inspection there were again no mechanical issues. Owner drove to dealer & was told to bring back the next day. Owner inquired if vehicle was safe to drive & was told "I hope so" by the service technician. GM customer care was called & stated they were not aware of any issues with the 2011 hd vehicles. Owner took vehicle to dealer next morning & several hours later was called & told it was mud in wheels (not possible since the first time it happened there was no mud). Owners son then looked on internet to see many people having the same issue in this model year vehicle. The son then found that a tsb was issued by GM to all dealers for a sticky break pedal that when stuck (even though it appears visually to not be stuck) will at random times cause the ABS to activate violently. Tsb# pit5037B. Dealer was then told by owner about the tsb & dealer was not aware of tsb. Repair was performed & the vehicle has not shook since. Owner was suppose to be pulling a 30 ft 5th wheel with a 15 ft trailer attached to it (45 ft. Total). If they had been they likely would have been in major accident with possible loss of life due to the sway it causes when it occurs.

- Filion, MI, USA