6 Major GMC Sierra 4 Wheel Drive Problems You Must Know

The GMC Sierra is a popular full-size pickup truck known for its performance, durability, and towing capacity.

The modern-day GMC Sierra was first introduced in 1999.

If you’re a proud GMC Sierra 4WD truck owner, you already know it’s a reliable vehicle.

However, like any mechanical or electrical device, it’s not immune to problems.

There are some common problems that many GMC Sierra owners complain about.

Most of them are minor problems, but some require expensive repairs.

6 Major GMC Sierra 4 Wheel Drive Problems and Solutions

Like other trucks, the GMC Sierra also has some major issues, including transfer case failure, fuel pump failure, front differential actuator failure, transfer case position sensor selector switch failure, fuel level sensor failure, and air conditioning malfunction.

1. Transfer Case Failure

Transfer Case Failure

Most 4WD GMC Sierra owners complain that they face problems with the transfer case.

The transfer case is a critical component of the 4-wheel drive system.

It transfers power to the front and rear axles as needed.

The transfer case motor is what engages and disengages the 4-wheel drive system.

So if it fails, you won’t be able to engage 4-wheel drive at all.

Symptoms of a Failed Transfer Case:

  • Flashing 4WD
  • Grinding and clicking noise
  • No response from the 4WD while engaging

The transfer case may fail because of wear and tear, electrical problems, or a lack of maintenance.


Check the transfer case fluid.

Low or contaminated fluid can cause problems with the transfer case, such as overheating or premature wear and tear.

If there is any issue with the fluid, refill it.

In most cases, a failed transfer case will need to be replaced.

An experienced truck mechanic can figure out what’s wrong and replace it with a new one or one that has been fixed.

The transfer case is expensive to fix, but it’s important to ensure the 4-wheel drive system works right to keep the truck from worsening.

2. Fuel Pump Failure

Fuel Pump Failure

Many GMC Sierra drivers complain they can’t start their trucks even though the fuel tank is full.

A damaged fuel pump causes it.

The fuel pump transfers fuel to the engine.

When it gets damaged, it fails to supply fuel to the engine.


There is no alternative except to replace the fuel pump, which has failed.

Visit an experienced auto mechanic to fix the fuel pump for you.

3. Front Differential Actuator Failure

Another common issue that GMC Sierra 4-wheel-drive owners face is the failure of the front differential actuator.

The front differential actuator is a component that engages and disengages the front differential in your truck.

It transfers power from the transmission to the front wheels when the 4-wheel drive is engaged.

A flashing 4WD light is the symptom of a failed front differential actuator when you try to engage the 4WD.

If dirt or debris gets inside the actuator, it can cause it to malfunction.

The front differential actuator can also be damaged if the vehicle collides with or hits a large object, such as a rock or curb.


Check the wiring and connections of the front differential actuator.

Sometimes the issue may be with something other than the actuator motor but rather the wiring and connections.

A mechanic should inspect the wiring and connections to ensure everything works well.

But if the front differential actuator motor is damaged, it must be changed.

4. Transfer Case Position Sensor Selector Switch Failure

Many drivers have complained about the failure of the 4-wheel drive transfer case position sensor selector switch.

This switch is a small but important part of the 4WD system.

This small switch is responsible for sending a signal to the vehicle’s ECU to indicate the position of the transfer case, allowing the ECU to engage or disengage the 4WD as needed.

When this switch fails, you will experience issues with the 4WD system, such as difficulty engaging the 4WD that engages and disengages on its own.

While off-road driving, the switch may become damaged by water and dirt.


Most of the time, the best way to fix this problem is to replace the 4WD transfer case position sensor selector switch.

The cost of this replacement is around $100.

5. Fuel Level Sensor Failure

Many 4WD GMC Sierra owners complain that the fuel gauge is not showing an accurate reading.

It occurs when the fuel level sensor fails.


If you experience this issue, immediately replace the fuel level sensor.

6. Heating and Air Conditioning Malfunction

Heating and Air Conditioning Malfunction

Another common problem that GMC Sierra owners face is a malfunction of the heating and air conditioning system.

When the blower motor of your air conditioning system fails, you will experience no airflow or reduced airflow.

A failure in the blend door actuator also causes the air conditioning system to malfunction.


If you face any issue with the air conditioning system, you need to pay a visit to an auto mechanic.

An experienced car mechanic will find the exact cause behind the malfunction.

The mechanic will find the exact cause of the malfunction.

If the actuator is damaged, you need to replace it.

Are 4WD GMC Sierras Reliable?

Yes, undoubtedly, the 4WD GMC Sierras are reliable and trustworthy trucks.

You must ensure regular truck maintenance to get the best performance.

With proper maintenance, the 4WD GMC Sierra will last over 350,000 miles.

On the contrary, if you don’t maintain your 4WD GMC Sierra regularly, it will last less than 150,000 miles.

Final Words

The GMC Sierra is one of the best trucks available on the US market.

Though it has some common problems with the 4WD system, it’s still user-friendly.

If you have any of these problems with your 4WD GMC Sierra, you should have it checked out by the dealer or an experienced auto mechanic.

Purchase and install replacement parts if necessary.

Always remember that only regular truck maintenance will provide a smooth driving experience.

Want to explore more GMC Sierra common problems? Check out the following articles:

Leave a Comment