2020 GMC Sierra Power Tailgate Not Working: Diagnosis & Fixes

Imagine you're at the hardware store, hands full, and you press the button to open your 2020 GMC Sierra's power tailgate, but nothing happens. No familiar whir, no click, just silence. This frustrating scenario, where the electronic release fails, forcing manual intervention, is a common complaint for owners of the 2020 GMC Sierra. When a premium feature like the power tailgate suddenly becomes unavailable, it's more than an inconvenience – it's a disruption to your truck's utility.

What drivers notice on this 2020 GMC Sierra

Owners of the 2020 GMC Sierra often report that their power tailgate, a key convenience feature, simply stops responding to electronic commands. This means the tailgate won't unlatch or lower using the key fob, the interior dash button, or the button located on the tailgate handle itself. The primary frustration stems from the loss of a feature designed for ease of use, requiring drivers to manually operate a system that should be automated.

At a glance: difficulty, repair cost, and diagnostic workflow

• Difficulty Rating: 6/10 — Moderate
• Common Symptoms: The tailgate does not unlatch electronically via the key fob, interior dash button, or tailgate handle button.; There is no audible click, whirring, or motor sound when attempting to open the tailgate.; The tailgate can still be opened manually, but the power assist or electronic release function is completely inoperative; Intermittent failures where the tailgate works sometimes but not others, before a complete failure.
• Estimated Repair Cost: $100–$900 (parts + typical shop labor)
• OEM Tooling Required: Standard OBD-II scanner and hand tools

Diagnostic workflow:

1. Confirm the symptom on your vehicle.
2. Scan for stored or pending codes with an OBD-II tool.
3. Inspect the most common causes in this guide (visual checks first).
4. Run verification tests before replacing parts.
5. Repair, clear codes, and verify on a test drive.

Symptoms and warning signs

When your 2020 GMC Sierra power tailgate is experiencing issues, you might observe several tell-tale signs:

• The tailgate does not unlatch electronically via the key fob, interior dash button, or tailgate handle button.
• There is no audible click, whirring, or motor sound when attempting to open the tailgate.
• The tailgate can still be opened manually, but the power assist or electronic release function is completely inoperative.
• Intermittent failures where the tailgate works sometimes but not others, before a complete failure.
• A warning message related to the tailgate might appear on the driver information center (DIC).

What is different on this year and model

The 2020 GMC Sierra, particularly models equipped with the MultiPro tailgate or similar power-assist features, incorporates a more complex electronic and mechanical system than traditional tailgates. This design includes multiple actuators, sensors, and a dedicated electronic control module that manages the tailgate's various functions. This added complexity means there are more potential points of failure compared to a simple, manually operated tailgate, making specific wiring harnesses and actuators unique to this advanced system.

How to verify and confirm the issue

Confirming the issue with your 2020 GMC Sierra's power tailgate involves a series of practical checks:

• Attempt all release methods: Try opening the tailgate using the key fob, the interior dash button, and the button on the tailgate handle. If none work, the electronic system is likely at fault.
• Listen for sounds: When attempting to open the tailgate electronically, listen closely for any sounds like clicks, whirs, or motor engagement. The absence of these sounds often indicates an electrical or mechanical failure within the release mechanism.
• Visual inspection: Carefully inspect the tailgate for any physical obstructions, debris, or obvious damage that might be preventing the latch from operating. Also, check for visible damage to the wiring harness where it enters the tailgate.
• Fuse check: Consult your owner's manual to locate the fuse for the tailgate release system, typically found in the underhood or interior fuse box. Inspect the fuse for any signs of being blown.
• Scan tool diagnostics: While not always an OBD-II code in the traditional sense, a professional-grade diagnostic scanner can often communicate with the Body Control Module (BCM) or a dedicated Tailgate Control Module. This can reveal specific fault codes related to the tailgate's electrical circuits, switches, or actuators.
• Battery voltage check: Ensure your vehicle's battery is fully charged and in good health, as low voltage can sometimes impact the operation of accessories like the power tailgate.

Common causes (most likely first)

The failure of your 2020 GMC Sierra's power tailgate can stem from several common issues:

• Faulty Tailgate Release Actuator: This is the electric motor responsible for physically unlatching the tailgate. It's a mechanical component subject to wear and tear.
• Damaged or Corroded Wiring Harness: The wiring that runs to the tailgate is exposed to the elements and constant movement, making it susceptible to fraying, breaks, or corrosion, particularly near hinges or flexible conduits.
• Blown Fuse: A simple electrical overload can cause the fuse protecting the tailgate circuit to blow, completely disabling the system.
• Faulty Tailgate Release Switch: The electronic buttons on the tailgate handle, key fob, or inside the cabin can fail due to internal electrical issues or wear.
• Body Control Module (BCM) or Tailgate Control Module Malfunction: Less common, but a software glitch or hardware failure in the vehicle's main control module or a dedicated tailgate module can prevent proper operation.
• Physical Obstruction or Damage: Debris, bent components, or even minor collision damage can physically impede the latch mechanism, preventing it from moving freely.

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Step-by-step diagnosis and fixes

Addressing a non-functioning power tailgate on your 2020 GMC Sierra involves a systematic approach:

• 1. Check Fuses: Begin by consulting your owner's manual to identify the exact location of the fuse(s) for the tailgate system. Replace any blown fuses with one of the correct amperage. This is often the simplest fix.
• 2. Inspect Wiring Harness: Carefully examine the wiring bundle that runs from the truck's chassis into the tailgate. Look for any signs of pinching, chafing, cuts, or corrosion, especially in areas of movement. Repair any damaged wires using appropriate connectors and heat shrink tubing.
• 3. Test Release Switches: Using a multimeter, test the continuity of the tailgate release switches (on the tailgate, dash, and key fob) to ensure they are sending a signal when pressed. This may require accessing the wiring behind the switches.
• 4. Test Tailgate Actuator: If power is reaching the actuator but it's not engaging, the actuator itself is likely faulty. You can sometimes test an actuator by applying 12V directly (following a wiring diagram carefully) or by checking for voltage at its connector when a release button is pressed. No voltage indicates a wiring or control module issue; voltage with no movement indicates a bad actuator.
• 5. Scan for Diagnostic Trouble Codes (DTCs): If you have access to an advanced diagnostic scanner, connect it to the vehicle's OBD-II port. Check the BCM or other relevant modules for any specific codes related to the tailgate system. These codes can provide valuable clues about electrical faults. For more general diagnostic information, you can explore various All repair guides.
• 6. Physical Latch Inspection: With the tailgate open, visually inspect the latch mechanisms on both sides for any debris, rust, or binding. Clean and lubricate any moving parts that appear stiff or obstructed.

Repair options and cost factors

The cost and complexity of repairing your 2020 GMC Sierra's power tailgate will vary significantly depending on the root cause:

• Fuse Replacement: This is the most inexpensive repair, typically costing only a few dollars for a new fuse.
• Wiring Repair: The cost can range from minimal for a simple splice to more significant if an entire section of the wiring harness needs replacement.
• Tailgate Release Switch Replacement: Parts are generally affordable, but labor costs can add up if extensive disassembly is required to access the switch.
• Tailgate Actuator Replacement: This is a more involved repair. The actuator is often integrated into the tailgate latch assembly, and OEM parts can be relatively expensive, in addition to labor for removal and installation. For more information about your specific model, check out the Sierra model hub.
• Control Module Replacement/Reprogramming: This is typically the most expensive and complex repair, often requiring specialized diagnostic tools and programming by a dealership or a qualified independent shop.

It is generally recommended to use genuine OEM parts for critical components like actuators and switches to ensure proper fit, function, and longevity.

When to see a professional

While some basic troubleshooting can be done at home, there are times when consulting a professional technician is the best course of action for your 2020 GMC Sierra power tailgate issue:

• If basic checks like fuse inspection and visual wiring assessment do not resolve the problem.
• When you lack the necessary diagnostic tools, such as a multimeter or an advanced scanner, or the expertise to safely diagnose complex electrical systems.
• If the issue appears to involve extensive wiring damage, internal component failure within the tailgate, or a problem with a control module that requires specialized programming.
• For any safety-critical repairs, especially if the tailgate's proper function affects cargo security or the overall structural integrity of the vehicle. For general information on GMC vehicles, visit our Gmc vehicle hub.

Frequently asked questions

Can a dead battery cause my 2020 GMC Sierra power tailgate not to work?

Yes, a severely discharged or failing battery can definitely cause the power tailgate to malfunction or not operate at all. The electronic system, including actuators and control modules, requires adequate voltage to function correctly, so ensuring your battery is fully charged and healthy is a good first step in diagnosis.

Is there a manual override for the 2020 GMC Sierra power tailgate?

While the 2020 GMC Sierra's power tailgate is electronically controlled, it typically includes a manual release mechanism in case of electronic failure. Accessing this usually involves opening an access panel on the inside of the tailgate to manually manipulate the latch, allowing you to open it without power.

How do I check the fuse for my 2020 GMC Sierra power tailgate?

To check the fuse for your 2020 GMC Sierra's power tailgate, refer to your vehicle's owner's manual for the exact fuse box diagrams and locations, which are usually under the hood or inside the cabin. Identify the fuse labeled for the

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This guide is not a substitute for OEM service procedures; use a qualified technician for safety-critical repairs.

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