2015 GMC Sierra 6 Speed Transmission Problems

The transmission is one of the important systems of your vehicle, and it has several interconnected parts. Most of these moving parts rub against, heat up, and interact with other components.

Thus, as most of your transmission parts endure heat and friction, they have a chance of wear and tear. Ultimately, you can find problems with your vehicle’s transmission. It is also true for the 2015 GMC Sierra 6-speed vehicle model.

The recent consumer reports have revealed that this pickup truck has lots of transmission problems. We will now discuss those common transmission issues with you.

2015 GMC Sierra has not received high ratings from the users due to its multiple transmission issues.

While some GMC Sierra owners are pleased with the vehicle’s performance, others have frowned over the low-quality transmission.

They have found both major and minor issues with the transmission. We have provided you with more details about those problems.

Some drivers have found the need to replace the 2015 GMC Sierra’s transmission when their trucks have covered only 66,000 miles.

One of the cons is that the manufacturer’s warranty does cover this transmission replacement.

You may need to pay about $3,000 to replace the vehicle’s transmission. As the transmission did not last longer than 2 to 3 years, some users felt frustrated.

Transmission replacement is one of the costly affairs for truck owners. However, the 2015 GMC Sierra’s transmission has several other minor problems.

We have listed those problems and the factors causing them.

2015 GMC Sierra Problems

1. Transmission slipping

The slipping problem turns up while your transmission system slips to a different gear. The system does not glide smoothly and causes this problem.

There may be more than one reason behind this slipping transmission. 

  • Burnt and low transmission fluid

The presence of low fluid may cause overheating problems. When the transmission fluid is not up to the right level, it can affect the hydraulic pressure needed to manage gears. You have to check the fluid level regularly.

Although the transmission remains sealed, there may be leakage. Moreover, the burnt fluid can emit a burnt smell that is easily detectable.

  • Failed solenoid

The electro-hydraulic valve-solenoid helps control the fluid flow through your vehicle’s transmission.

The malfunctioning solenoid may cause the release of fluid.

  • Torque converter problems

This converter gets power from the engine to ensure its conversion into torque.

However, any problem with the torque converter prevents the smooth of fluid, and you will find slipping transmission.

  • Worn-out transmission gears

Due to regular use, these gears start wearing out. You may find gears not fitting together properly.

You will feel a jerky shifting. Transmission bands connected to gears may deteriorate over time, and you have to replace them.

  • Defective clutch

There is a series of clutches with every transmission, and they help manage gears.

Clutches in the automatic remain integrated into the converter locked up at high speed to avoid slipping problems in your transmission.

Thus, when you find defects in the clutch, you have to repair it without any delay.

2. Jerking transmission

It is another common problem reported by the 2015 GMC Sierra pickup truck owners.

These truck drivers have felt rough shifting and lack of smooth transmission. There may be different reasons behind this transmission issue.

  • The transmission fluid level is low

We have already discussed the transmission fluid problems causing hard shift conditions.

Lack of lubrication may cause serious complications. Your transmission fluid must be light red and clean with a transparent look.

  • Faulty sensor

The integrated sensors help communicate to the internal computers, and some of them affect the transmission shifting process.

When these sensors do not work properly and receive incorrect data, they can result in wrong shifting. Faulty sensors are one of the causes of transmission issues.

  • Delayed gear shift

 It is one reason behind the failed transmissions. You can find a delay in response taken from shifting into the moving gears.

The delay duration can range from a few seconds to minutes. You must not overlook this delayed engagement, as it indicates a problem with your transmission.

In most cases, failed solenoids and improper fluid maintenance can cause the delayed engagement.

3. Transmission Sound

According to consumer reports, 2015 GMC Sierra drivers have heard some metallic noise from their transmission system. Based on the type of noise, you may detect the transmission issue.

  • Whining

While operating the pickup truck, you can find a whining sound generated by the transmission.

However, there may be different factors resulting in this sound. The whining noise can gradually make your transmission deteriorated.

The noise also indicates a clogged transmission fluid line, and you have to repair it instantly. You may rely on a professional solution to deal with this problem.

  • Grinding

In some cases, you can hear grinding noise coming out of your transmission. However, this grinding noise can indicate a serious transmission problem.

The source of the problem can be a planetary gear system. This gear system is directly related to your automatic transmission.

When this system cannot work, you may find complicated problems with your transmission.

The whining noise mostly denotes issues with the planetary gear system. You have to check the system regularly for proper maintenance. Diagnose the problem rightly and repair it.

  • Gurgling

When the transmission fluid is not at the proper level, you can hear this gurgling noise. The transmission line producing a high amount of air can cause noise.

However, this noise also indicates the slipping transmission, one of the common problems with the 2015 GMC Sierra 6-speed pickup trucks.

Check the fluid level to solve the issue. Still, when you cannot find the reason behind the gurgling noise, you can look for technicians.

We have discussed the common transmission problems of the 2015 GMC Sierra. From analyzing customers’ comments, we have learned about these transmission issues.

However, with minor repairs, you can manage these problems and have a comfortable ride. When you cannot solve them with DIY methods, you may look for professional help.

Liam Dare

As CEO of ReplicarClub.com, my passion for the automotive world motivates me to build online businesses that provide information and entertainment to users. I am proud to contribute in a positive way to the automotive community.