The GMC Sierra 1500 is a popular light-duty truck for its durability and power.
After launching the first-ever GMC Sierra 1500 in 1988, it became a favorite among truck enthusiasts.
The GMC Sierra is available with three different transmission options: 6-speed automatic transmission, 8-speed automatic transmission and 10-speed automatic transmission.
From the beginning, after the first generation of the GMC Sierra 1500 had launched, it had some issues regarding transmission.
General Motors Company regularly updated and tried to fix these issues.
But still, there are some common issues with the GMC Sierra 1500 transmission.
In this article, I’m going to share with you these common GMC Sierra transmission problems and their solutions.
In addition to this article, you might find these resources helpful:
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- Causes and solutions to GMC Sierra power outlet not working
- GMC Sierra 4 wheel drive problems and solutions
GMC Sierra 1500 Transmission Problems [05 Common Problems and Solutions]
Being a professional mechanic for years, I have seen 05 common problems associated with the transmission system in almost all GMC Sierra 1500 trucks, including bad gear shifting, shaking and shuddering, slipping gears, overheating and clunking sounds.
01. Bad Gear Shifting
Many GMC Sierra 1500 owners experience shifting issues with the transmission.
Sometimes the transmission hesitates to shift gears.
It seems like the transmission doesn’t know which gear to change next.
Mostly, low transmission fluid causes this issue.
Erratic shifting is another problem that the GMC Sierra owners face.
It occurs when the transmission shifts too quickly or slowly.
A faulty transmission control module (TCM) is responsible for that.
Solution
If you are experiencing shifting issues with your GMC Sierra 1500, you should not ignore it.
It can lead to further damage.
Check the transmission fluid level if the fluid level is low.
Try to keep the transmission fluid level up to the mark.
Check the transmission control module.
If there is any fault in the transmission control module, take the help of a professional mechanic to repair it.
02. Shaking and Shuddering
Shuddering in the transmission is another common issue that some GMC Sierra 1500 owners experience.
You can feel that the transmission is vibrating while shifting gears.
When the transmission fluid level is low or becomes dirty, shuddering occurs.
It also can happen when the torque converter is worn out.
Solution
If you notice your truck is shuddering or vibrating.
Check the transmission fluid level.
If it is low, refill the transmission fluid.
But if it is dirty or contaminated.
Change the transmission fluid immediately.
You also should check the torque converter.
If the torque converter is worn out, it must be replaced.
03. Slipping Gears
Another common problem with the GMC Sierra 1500 transmission is slipping gears.
When the transmission leaks fluids, the fluid level starts to decrease.
So the transmission fluid level gets low very quickly.
And the transmission starts to misbehave and may not work properly.
This results in slipping gears or a delayed response when shifting.
If the bolts that hold the transmission pan attached to the vehicle become loose, fluid can leak out.
Worn or damaged seals also can cause transmission fluid leaks.
A cracked transmission pan might be another reason to leak out the fluid.
Solution
If you notice your transmission fluid level is getting low quickly, look beneath your truck.
Try to find the exact cause of the fluid leaks.
If you find any crack in the transmission pan, repair or replace it immediately.
Check the bolts and ensure that they are tight enough.
If the seals are damaged, the seals need to be replaced.
04. Transmission Overheating
Transmission overheating is another common problem for the GMC Sierra 1500.
The transmission transfers power from the engine to the wheels.
So it generates a significant amount of heat.
It can cause damage to the transmission components and lead to other problems as well.
When the transmission is overheating, you can sense a burning smell.
Overheated transmission can cause slipping gears or jerky shifts.
Low or dirty transmission fluid, overloading or towing, and a faulty transmission cooler cause transmission overheating.
Solution
The transmission temperature warning light will indicate if the transmission is overheating.
It is important to address the actual reason why the transmission is overheating.
Check the fluid level.
If the fluid level is low or dirty, change the transmission fluid.
If the vehicle is overloaded, reduce the load on the transmission.
And if there is any fault in the transmission cooler, repair or replace it.
05. Clunking Sounds
Clunking sound in the GMC Sierra 1500 is another common issue.
You can hear unusual sounds while shifting gears.
Transmission can create clunking sounds for various reasons.
The transmission mounts hold the transmission in place.
If the transmission mounts become worn, they can cause the transmission to move around and create clunking sounds.
The U-joints transfer power from the transmission to the driveshaft.
If they become damaged, they create clunking sounds.
CV joints connect the wheels to the transmission.
Damaged CV joints are also responsible for unusual sounds.
Solution
If you experience any unusual sounds from the transmission.
Try to inspect the original reason behind that.
If any of the transmission mounts, U-joints or CV joints are damaged, repair or replace them with the help of an experienced mechanic.
GMC Sierra 2500 Transmission Problems
The GMC Sierra 2500 is a heavy-duty truck manufactured by General Motors under the GMC brand.
Like other GMC Sierra trucks, it also uses the Allison automatic transmission.
Recent year models of the GMC Sierra 2500 use 10-speed automatic transmission.
Although it is a reliable transmission system, there are still 05 common problems with GMC Sierra 2500 transmission.
- Delayed shifting
- Leaking fluids
- Shuddering or vibration while shifting gears
- Transmission slipping
- Faulty torque converter
Final Thoughts
If you own a GMC Sierra 1500, it’s important to keep an eye out for these common transmission problems.
If you notice any issues with your transmission, it will be better to inspect it by a professional mechanic as soon as possible.
Otherwise, it can lead to further damage and costly repair.
Remember, regular maintenance can prevent transmission problems from occurring in the first place.
