If your GMC Sierra or other GM truck is plagued by bizarre electrical problems, you’ve come to the right place. As a technician with over two decades of experience, I’ve seen firsthand how a failing Body Control Module (BCM) can turn a reliable truck into a source of constant frustration. This isn’t just a part; it’s the central command for your vehicle’s comfort and convenience features. This OEM-quality BCM, part number 20939138, is the definitive, hassle-free solution to restore full functionality to your vehicle.
We take the guesswork and expensive dealership trips out of the equation. Each module is expertly programmed to your vehicle’s specific VIN before it ships. This means no extra programming fees or special tools are required for installation. It arrives ready to install, allowing you to solve complex electrical issues right in your own driveway.
Is Your Truck Showing These Symptoms?
A faulty BCM can manifest in numerous ways that seem unrelated. If you’re experiencing any of the following, this module is the likely fix you need.
- ✔ The air conditioning or heater blower works intermittently or not at all.
- ✔ Your airbag warning light is on, often with a diagnostic trouble code (DTC) like B1001.
- ✔ Power windows, door locks, or interior/exterior lights behave erratically or have stopped working.
- ✔ The security system malfunctions, causing no-start conditions, stalling, or misfires.
- ✔ Your scan tool shows various communication or body-related DTCs that won’t clear.
A Technician’s Notebook: The Case of the Ghostly Glitches
A customer brought in his ’09 Silverado 2500, convinced it was haunted. The radio would change stations on its own, the dome light would flicker, and the power locks would cycle while driving. He’d already replaced the battery and checked the main grounds. After hooking up my scan tool, I saw a dozen intermittent communication codes pointing to the BCM. These modules are notorious for internal solder joint failures and grounding path issues over time. We swapped in a VIN-programmed BCM, and within 10 minutes, every single ghost was gone. It’s a common story for these otherwise bulletproof GMT900 trucks.
A Straightforward Guide to Installation
Replacing your 2007-2011 Sierra 2500 BCM is a simple job that most DIYers can complete in under 15 minutes. The module is located under the driver’s side dashboard, near the steering column.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before working on electrical components.
- Locate the BCM: Find the module under the driver’s side dash. It will have several large electrical connectors attached to it.
- Disconnect and Remove: Carefully unplug all electrical connectors. They have locking tabs that need to be depressed. Once disconnected, unclip or unbolt the old module from its mounting bracket.
- Install the New Module: Snap the new, pre-programmed BCM into the mounting bracket and firmly reconnect all electrical harnesses. You will hear a click as they lock into place.
- Reconnect and Test: Reconnect the negative battery terminal. Start the vehicle and test all functions: lights, wipers, locks, windows, and HVAC to confirm the repair.
- Post-Install Check: In some cases, the airbag light may remain on. This requires a professional scan tool to perform the ‘Setup SDM Primary Key in BCM’ function to sync the systems. A brake pedal position relearn may also be needed for certain models.
Guaranteed Fitment for Your GM HD Truck
This module is a direct replacement for part number 20939138 and is interchangeable with several other part numbers, including 25844480, 25835966, 15943678, and 22860591. It is guaranteed to fit the following vehicles:
Chevrolet: Silverado 1500/2500/3500 (2007-2013), Avalanche 1500 (2007-2011), Suburban 1500/2500 (2007-2011), Tahoe (2007-2011)
Cadillac: Escalade, ESV, EXT (2007-2011)
Note: Please verify your part number or consult the detailed fitment list to ensure compatibility. For 2007 models, this fits the ‘new style’ with a smooth door skin.
Frequently Asked Questions
Does this BCM really come programmed to my VIN?
Yes. We program each module with the latest GM software using the VIN you provide during checkout. This ensures it works correctly with your vehicle’s specific options right out of the box.
Do I need to send my old BCM back? Is there a core charge?
No. We do not require a core return for this part. You can keep your old module, saving you the time and expense of shipping it back.
What tools do I need for the installation?
For most installations, you’ll only need a basic socket or wrench to disconnect the battery terminal and possibly a trim removal tool to access the BCM. No special programming tools are required.
My airbag light is on after installing. What do I do?
This is a normal security measure in some GM vehicles. The BCM and the airbag system (SDM) need to be electronically re-synced. This requires a bi-directional scan tool to perform the ‘Setup SDM Primary Key’ procedure. A local repair shop can typically perform this service.
Is this a reliable, long-term fix?
Absolutely. This module is built to OEM specifications to ensure durability and performance. It’s backed by our one-year warranty, giving you peace of mind that you’re making a lasting repair.