Fix Your Avalanche’s Electrical Gremlins for Good
If you’re dealing with baffling electrical issues in your 2007-2011 Chevrolet Avalanche 1500—like climate controls that have a mind of their own, power windows that won’t budge, or a security light that won’t turn off—you’ve likely met the culprit: a failing Body Control Module (BCM). As the central command for your truck’s body electronics, a faulty BCM can cause a cascade of frustrating and unpredictable problems. This replacement BCM, part number 20939137, is the definitive, hassle-free solution. It arrives expertly programmed to your truck’s specific VIN, eliminating the need for expensive dealership visits and getting you back on the road with confidence.
Is Your Avalanche Showing These Telltale Signs?
A failing BCM doesn’t always trigger a check engine light. Instead, it manifests as a variety of strange electrical behaviors. In my 20+ years of diagnostics, these are the most common symptoms I’ve seen point directly to a bad BCM on this GM truck platform:
- ✔ Intermittent or completely dead HVAC and blower fan controls.
- ✔ Power windows, door locks, or interior/exterior lights not working correctly.
- ✔ The airbag warning light is on, often with a Diagnostic Trouble Code (DTC) like B1001.
- ✔ Vehicle security system malfunctions, causing no-start or stalling conditions.
- ✔ Unexplained battery drain or bizarre grounding-type issues.
- ✔ Wipers or other accessories activating on their own or not at all.
A Technician’s Notebook: The Case of the Phantom Airbag Light
A customer brought in his ’09 Silverado with an airbag light that two other shops couldn’t fix. They had already replaced the BCM, but the light remained. After plugging in my scanner, I saw the familiar B1001 code. The issue wasn’t the new BCM; it was that the previous installers missed a critical final step. The Sensing and Diagnostic Module (SDM) needs to ‘handshake’ with the new BCM by transferring its primary key. Using my scan tool’s special functions, I performed the ‘Setup SDM Primary Key in BCM’ procedure. In less than a minute, the systems synced, and the light went out for good. This is why our pre-programmed modules and clear post-install instructions are so crucial—they account for the real-world complexities of the repair.
A Straightforward Guide to Installation
One of the best features of this module is its simple installation. You don’t need a vehicle lift or complex tools—just a few minutes and some basic hand tools. This makes it a perfect job for a DIY enthusiast looking to save on labor costs.
- Safety First: Always disconnect the negative terminal from your truck’s battery before working on any electronic components.
- Locate the BCM: On your Avalanche, the BCM is located under the driver’s side of the dashboard, typically to the left of the steering column.
- Swap the Module: Carefully unplug the electrical connectors from the old BCM. They have locking tabs, so be gentle. Remove the old module and install the new one in its place.
- Reconnect and Test: Securely plug the connectors into your new BCM. Reconnect the battery terminal. Start the truck and test all functions—lights, locks, windows, HVAC, etc.—to confirm the repair.
- Final System Checks: As noted in our technician’s story, if the airbag light is on, a ‘Setup SDM Primary Key’ procedure is needed with a capable scan tool. Some models may also require a ‘Brake Pedal Position Relearn’ to ensure proper brake light and traction control operation.
Verified Vehicle Compatibility
This Body Control Module is a direct-fit replacement for a wide range of General Motors trucks and SUVs, ensuring OEM-level performance and integration. While this page is focused on the 2007-2011 Avalanche 1500 BCM, it is also compatible with the following vehicles. Please match your part number (20939137) or one of the interchangeable numbers to guarantee fitment.
Note: For 2007 models, this fits the ‘new style’ with the smooth door skin. Always verify your part number. Interchangeable with: 25835966, 15943678, 25971916, 20939138, 22860591 and more.
Frequently Asked Questions
What does ‘VIN Programmed’ actually mean for me?
It means we load your truck’s specific Vehicle Identification Number (VIN) and all related software onto the module before we ship it. This ensures it works perfectly with your vehicle’s existing systems right out of the box, saving you from a mandatory and costly programming session at a dealership.
Is this BCM difficult to install myself?
Not at all. The physical replacement typically takes less than 10 minutes with basic tools. It’s located under the driver’s side dashboard and just involves swapping a few electrical connectors.
Will this part fix my airbag warning light?
It often does, as a faulty BCM can cause airbag communication codes like B1001. However, after installation, you may need a professional scan tool to perform an ‘SDM Key Sync’ to get the new BCM and the airbag system to communicate properly and turn off the light.
What is your policy on core charges?
We have a simple policy: there is no core charge. You are not required to send your old, faulty module back to us, which saves you time and return shipping costs.
How do I know if the BCM is the problem and not something else?
While the symptoms listed are strong indicators, the best way to be certain is with a professional diagnosis. A scan tool that can communicate with the BCM is essential. Common signs include multiple communication codes (U-codes) or specific B-codes related to body components. Also, checking major ground connections is a good first step.