2020 GMC Sierra 2500HD Key Fob Programming Guide

Quick Reference

Step-by-Step On-Board Programming

Unfortunately, the 2020 GMC Sierra 2500HD does not support DIY, on-board programming for key fobs. This means you cannot program a new key fob yourself using a sequence of actions like turning the ignition on and off or pressing buttons in a specific order.

To program a new key fob for your 2020 GMC Sierra 2500HD, you will need specialized diagnostic equipment. This typically involves a scan tool that connects to the vehicle's On-Board Diagnostics (OBD-II) port to communicate with the vehicle's computer system. This process is usually performed by a dealership or a qualified automotive locksmith.

Why a Specialist Is Required

Modern vehicles like the 2020 GMC Sierra 2500HD incorporate advanced security systems, including an immobilizer. The key fob not only provides remote functions (lock, unlock, remote start, etc.) but also contains a transponder chip. This chip communicates with the vehicle's immobilizer system. If the transponder's code doesn't match what the vehicle expects, the engine will not start, even if the key blade fits the ignition. Programming these systems requires specific software and access to security codes that are only available to authorized personnel or through advanced locksmith tools.

Battery Replacement

If your existing key fob isn't functioning correctly, the most common and easiest fix is to replace the battery. The 2020 GMC Sierra 2500HD key fob typically uses a CR2032 coin cell battery.

1. Locate the small slot or button on the side or bottom of the key fob. This is usually where you can separate the two halves of the fob.
2. Carefully use a small flat-head screwdriver or a coin to pry the two halves apart.
3. Once open, you'll see the circuit board and the battery. Note the orientation of the battery (positive (+) side up or down) before removing it.
4. Gently pop out the old CR2032 battery.
5. Insert the new CR2032 battery, ensuring it's oriented correctly.
6. Snap the two halves of the key fob back together until it's securely closed.

Test your key fob to ensure it's working after replacement.

Where to Buy a Replacement Fob

When considering a replacement key fob, you have a few options, each with pros and cons:

• Dealership:

  • Pros: Guaranteed genuine OEM part, expert programming. If you need a new key blade cut and programmed, they can do it all in one visit.
  • Cons: Typically the most expensive option. Expect to pay anywhere from $250 - $450+ for the fob and programming.

• Automotive Locksmith:

  • Pros: Often more affordable than a dealership. Locksmiths have the necessary diagnostic tools to program most vehicle key fobs, including those with immobilizer systems. Many can also cut and program new key blades on-site.
  • Cons: Ensure the locksmith is reputable and experienced with newer vehicle systems. Pricing can range from $150 - $350+, depending on the fob type and labor.

• Online Retailers (e.g., Amazon, eBay):

  • Pros: Generally the cheapest option for the fob itself. You can find both OEM and aftermarket options.
  • Cons: You're only buying the physical fob; you'll still need to have it programmed and potentially have a key blade cut. Be cautious about counterfeit or low-quality fobs. The cost for the fob might be $50 - $150, but you still need to factor in programming and cutting costs from a locksmith or dealer.

If On-Board Programming Isn't Supported

As mentioned, your 2020 GMC Sierra 2500HD requires specialized equipment for key fob programming due to its advanced immobilizer system. This means you will need to budget for professional services.

• Total Cost Expectations: When purchasing from a third party (like online), remember to add the programming fee (typically $75 - $150) from a locksmith or dealership to the cost of the fob. If you need a new key blade cut and programmed for the immobilizer, that will be an additional cost, usually ranging from $50 - $100 on top of the fob and programming fees.
• Immobilizer Transponder: The 2020 GMC Sierra 2500HD utilizes a sophisticated immobilizer system. Any new key, even if it's just a physical blade to open the door, must have its transponder chip programmed to the vehicle's immobilizer to allow the engine to start. Without proper programming, the vehicle will not recognize the key, and the engine will not crank or start.

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