End the Electrical Headaches in Your GM Truck
If your GMC Sierra or Chevrolet Silverado is acting possessed—with flickering lights, a dead HVAC blower, or random warning messages—the Body Control Module (BCM) is the likely culprit. As a technician with over two decades of experience, I’ve seen how a failing BCM can turn a reliable workhorse into a source of constant frustration. This isn’t just an inconvenience; it affects your truck’s core functions. This replacement Body Control Module, part number 20939137, is the definitive, hassle-free solution. We pre-program it to your truck’s specific VIN, so it arrives ready for a true plug-and-play installation, getting you back on the road without a mandatory trip to the dealership.
From the Diagnostic Bay: The Grounding Gremlin
A customer brought in his ’09 Silverado 2500 with a laundry list of bizarre issues: the radio would cut out, the dome light wouldn’t work, and the truck would occasionally refuse to start. He’d already replaced the battery and alternator. After hooking up my scanner, I saw multiple communication loss codes (U-codes) pointing to the BCM. Before condemning the module, I always check the main BCM ground—it’s a common failure point on these GM trucks. Sure enough, it was corroded. We replaced the BCM and cleaned the grounding point, and all the issues vanished. This is why I always tell my customers: when you install your new 2007-2011 Sierra 3500 BCM, take five extra minutes to inspect and clean the ground connection. It’s the best insurance against future problems.
Is Your Truck Showing These Symptoms?
A faulty BCM can manifest in numerous ways. If you’re experiencing any of the following, it’s time to consider a replacement:
- ✔ Power windows, door locks, or mirrors operating intermittently or not at all.
- ✔ The security or anti-theft system preventing the engine from starting.
- ✔ An illuminated airbag light, often with Diagnostic Trouble Code (DTC) B1001.
- ✔ HVAC controls are unresponsive, or the blower motor works sporadically.
- ✔ Headlights, taillights, or interior lights behaving erratically.
- ✔ Unexplained battery drain that leaves you with a dead vehicle overnight.
A Straightforward Guide to Installation
Replacing the BCM is a job most DIYers can handle in their own driveway. The module is typically located under the driver’s side dashboard, near the steering column.
- Step 1: Safety First. Always disconnect the negative terminal from your vehicle’s battery before working on any electronic components.
- Step 2: Locate the BCM. On most Sierra and Silverado models, you’ll find it attached to a bracket beneath the steering column. You may need to remove a lower dash panel for access.
- Step 3: Disconnect and Remove. Carefully unplug the electrical connectors from the old BCM. They have locking tabs that need to be depressed. Once disconnected, remove the module from its mounting bracket.
- Step 4: Install the New Module. Mount your new, pre-programmed BCM and securely plug in all the connectors. You should hear a click as they lock into place.
- Step 5: Reconnect and Test. Reconnect the battery terminal. Turn the key to the ‘On’ position and test all functions: lights, locks, windows, wipers, and the HVAC system.
- Step 6: Post-Installation Checks. If the airbag light is on, a ‘Setup SDM Primary Key’ procedure may be needed with a capable scan tool. Some models may also require a Brake Pedal Position relearn.
Verified Vehicle Compatibility
This module is a direct replacement for part number 20939137 and is interchangeable with several other part numbers, including 25844480, 25835966, and 22860591. It is guaranteed to fit the following vehicles:
Escalade, ESV, EXT (2007-2011)
Chevrolet:
Avalanche 1500 (2007-2011)
Silverado 1500 (2007-2011)
Silverado 2500/3500 (2007-2011, plus some 2013 models)
Suburban 1500/2500 (2007-2011)
Tahoe (2007-2011)
GMC:
Sierra 1500 (2007-2011)
Sierra 2500/3500 (2007-2011, plus some 2013 models)
Sierra Denali (All models, 2007-2011, plus some 2013 models)
Yukon & Yukon XL (2007-2011)
Note: For 2007 models, this fits the ‘new style’ with the smooth door skin. For certain 2010 and 2013 models, please verify your original part ID is 25835966 for compatibility. When in doubt, contact us with your VIN.
Frequently Asked Questions
Do I need to take my truck to the dealership after installation?
No. This BCM is delivered fully programmed to your vehicle’s VIN. This eliminates the need for expensive dealership programming, making it a true plug-and-play part.
How do I provide my VIN for programming?
You can enter your 17-digit VIN in the designated box on the product page or during the checkout process. We cannot ship the module until we receive your VIN.
What happens if my airbag light stays on after installing the new BCM?
This is a known security handshake procedure on GM vehicles. You will need a professional-grade scan tool to perform the ‘Setup SDM Primary Key in BCM’ function to sync the modules and clear the light. Most local repair shops can perform this for you.
Is this a new or used part?
This is a high-quality, OEM-standard replacement part, inspected and programmed to ensure reliability. It comes with a one-year warranty for your peace of mind.
Is there a core charge for my old BCM?
No, there is no core charge. You can keep your old part, so there’s no need to worry about return shipping or waiting for a refund.