GMC Transmission
General Motors Company, also known as GMC, is an American corporation that has its headquarters in Michigan. GMC designs, manufactures, markets, and distributes vehicles as well as parts. Although it is one of the world’s largest automobile manufacturers, there are plenty of troubles with the transmissions in their vehicles.
It began with William C. Durant's Durant-Dort Carriage Company. He had become the largest manufacturer of horse-drawn vehicles in the United States by 1900. Shortly after he moved on to automobiles. GMC was founded in 1908, and although it was restructured in 2009 it continues to be a successful company. Between 1931 to 2007 GMC was on top as the world's largest automaker.
In 2020, GMC ranked number 18 on the Fortune 500 by total revenue. Manufacturing vehicles in various countries, there are four main brands under GMC, Chevrolet, Buick, GMC, and Cadillac.
What Does a Transmission Do?
Not all car owners understand their transmission because it is an extremely complex part of a vehicle. It can be difficult to know what is wrong or how to find out what is wrong unless you are trained to know the problems.
Your transmission brings the power from your engine or motor and delivers it to the wheels. The transmission plays a key role in controlling your car, and it cannot function without it. It is responsible for ensuring the power created in your motor, gets to where it needs to be in order to move the car.
The transmission also works to maximize the efficiency of your car. You may be able to reduce fuel consumption without negatively impacting your driving. For example, when taking off from a stoplight, the transmission starts in a low gear. This gives more torque at lower RPMs and allows you to be able to get the wheels moving. Another example is during highway driving. This is when the transmission uses a gear with a much higher ratio to move the vehicle at higher speeds but still keeps the RMPs as low as possible.
Manual Transmission
There are two main types of transmissions, automatic and manual. Automatic transmissions are now more popular, but manual transmissions are easier to work on. Manual transmissions are made up of gears, output shafts, and input shafts. The gears of one shaft will work with the gears from other shafts.
When using a manual transmission, one gear is selected by the driver. The driver needs to move the shift lever in order to change the gear. This then controls the movement of the gear in the input shaft. Each link will work with two gears and can be done by shifting left or right. The clutch pedal will be engaged once pushing it, which is the main difference between an automatic and a manual transmission. Next, the gear is selected and the clutch is released. This must be done each time to shift gears.
Automatic Transmission
An automatic transmission is completely different and works in a similar manner. The main difference is that it works on its own without the driver needing to trigger it. In an automatic transmission, there is a torque converter that works with the gear set and the engine. Sometimes an automatic transmission offers the option to switch into manual mode with handlebar shifters or a stick shift, but without a clutch pedal.
Signs of a Bad GMC Transmission
Minor transmission repairs involve replacing defective solenoids, or re-sealing for leaks and replacing parts, even a throttle cable adjustment. Major transmission repair can often include disassembling, inspection, cleaning, or rebuilding. There are a few specific signs of a bad GMC transmission that are important to keep an eye out for.
Weird Smells
If you ever smell some type of burning it is essential to check this out right away. It might be your transmission fluid burning. As transmission fluid runs low it will overheat. This can make your engine overheat and run hot, which will eventually wear down on the car and cause corrosion.
Other causes of burning smells might include trapped plastic, dripping antifreeze, or a melting heater core. Be sure to get burning smells checked out regardless of their cause.
Odd Noises
Anytime you hear odd noises such as clunks it could be a flat tire or faulty starter, but it may also be your transmission. Any type of . You may hear machine-like sounds in a faulty manual transmission. Clunk noises while shifting gears are the best indicator of a manual transmission.
Extreme Noise
Excess noisiness may indicate a problem and it may show itself while in neutral. In this case, you will need to have an engine check. This is typically an easy fix, and it can be low fluid or that the wrong fluid was used. In the worst case, it might be a problem with your bearings or gear teeth, which may need replacements.
Check Engine Light
Many drivers ignore their check engine light, but this is not a good plan. Any type of red or blinking check engine light may be a sign of a serious transmission problem in GMC. There are sensors that essentially set off this light. Although sometimes they are no cause for concern, if a transmission s sensor sets it off, then there is.
No Response From Vehicle
When you have a functioning transmission it will go into the right gear. Whether you put it into the gear in a manual car, or you have an automatic car that simply does it for you, there should be no hesitation. No response means that there is something wrong with the transmission. Especially in a manual vehicle, this delayed shifting may also show an RPM surge and engine noise that is too loud for your speed. Although it could be the clutch, you won’t know until you take it in for servicing.
Fluid Leaking
There are six different types of fluid in a vehicle and they help your car to brake, steer, and even lubricate your car. When these leak or break it causes your car to malfunction. An automatic transmission is quite obvious when leaking. It is distinguished by its red color and sweet smell. In some cases it can be a bit darker and smell burnt, this means it needs to be replaced.
Finding a leak can be easily found by seeing bits of red or brown fluid on your driveway or in the street. In order to check this, drive for a few minutes to warm up the engine and then check using the dipstick located in the transmission. You should see an indentation to mark the proper fluid level.
The only time your transmission fluid might be lower is if there is a leak because it does not burn off as engine oil does. Add a bit to see if it stays and if not then you will need to re-seal your transmission.
Dragging Clutch
Though it's not a problem for automatic transmissions, dragging clutches are a serious issue for manual transmission vehicles. When there is extra slack in the clutch pedal it can make it more difficult for the clutch disc to disengage. This eventually leaves the clutch spinning and does not allow it to transfer power to the drivetrain. This makes it impossible to change gears and will show itself as a grinding sound.
Shaking
Having a GMC that is shaking is never a good situation and is a known situation. Normal transmissions will but in some cases you may notice shaking. This is a sign of an issue with your gears. If it is manual, you may need to replace your clutch.
Slipping Gears
If your vehicle requires an external input in order to change gears, it can cause your gears to slip. When it comes to a manual transmission, the driver must change each gear, but in an automatic, the driver reverses, places into neutral, and drives. If the car slips between gears then it can be dangerous to drive, but also damaging to your engine. One cause for this may include having low fluid levels. Another cause might be worn, transmission bands.
Common GMC Transmission Issues
If there is a transmission issue that requires immediate attention, then you might see one of the following messages on your GMC vehicle:
- Service transmission: This message will show if there is a general issue with the transmission. The best course of action is to have a transmission service performed.
- Shift to park: This message displays when the transmission needs to be shifted to Park. It will show itself when you try to remove the key from the ignition if it is not in park.
- Transmission hot-idle engine: This message will display and a chime will sound if the transmission fluid becomes hot. Driving with fluid temperature on high may cause damage to your car so this is essential to check on it. To see if this is serious, stop the vehicle and let it idle. This should allow the transmission to cool. It should go away when the temperature reaches a safe level.
Common Transmission Issues in GMC Models
Defective 8 Speed Transmissions
It was found that in many GMC models built between 2015 and 2019, there was a defect in their 8-speed transmissions. After spotting the lawsuit, it was found that there were serious problems with the GM Hydra-Matic 8L90 and 8L45 transmissions.
Transmissions have a defect that causes vehicles to hesitate and jerk when accelerating, but also when coming to a stop. The lawsuit stated that the common defect was reported because the shift was sometimes so violent, that it felt as though the car had been hit.
In one case, an owner had a vehicle that shifted from reverse to drive so harshly that it went through his garage door. The center around the transmission itself and the torque converter began shuddering. It also began jerking and hesitated to cause internal issues. Metal shavings ended up being found throughout the transmission.
Eventually, this class-action lawsuit also alleged that the metal shavings caused damage over time. This made GMC cars and trucks with transmission issues dangerous to drive. Since 2015, there have been thirteen Technical Service Bulletins and GMC has not fixed the problem.
Lawsuit Affecting GMC Vehicles
The lawsuit includes all vehicles that are equipped with the Hydra-Matic 8L90 or 8L45 transmissions, this includes:
- 2015-2019 GMC Sierra
- 2015-2019 GMC Yukon and Yukon XL
- 2015-2017 GMC Yukon Denali and Denali XL
- 2017-2019 GMC Canyon
There are six statewide classes that have been presented on behalf of GMC owners with these transmissions. This occurred in California, Florida, Illinois, Oklahoma, New York, and Texas. Although GMC has no commented on this, it is definitely an issue.
Class Action Lawsuit Against GMC
The “Chevy Shake” is a common class-action lawsuit that was brought against GMC. This shaking malfunction causes severe vibrations due to faulty aluminum driveshafts. The Chevy shake is something that GMC is aware of, and has not properly notified consumers. This lawsuit is class-action and is very serious.
The class-action lawsuit stated that GMC did not notify their consumers that they knew about the dangers of this issue. They did not display this information and continued to release these vehicles with dangerous transmissions.
Average Cost of GMC Transmission Repairs
