Fix Your Truck’s Electrical Problems for Good
Is your 2007-2011 GMC Sierra 1500 acting possessed? Flickering lights, a dead climate control, power windows with a mind of their own—these are classic signs of a failing Body Control Module (BCM). As the central command for your truck’s electronics, a faulty BCM can cause a cascade of frustrating and hard-to-diagnose issues. This OEM-quality replacement, part number 20939137, is the definitive solution. We pre-program it to your truck’s specific VIN, so it arrives ready for a true plug-and-play installation, eliminating the need for an expensive trip to the dealership.
Case Study: A Tricky Diagnosis
I once had a 2009 Sierra in the shop where the owner had already replaced the battery, alternator, and multiple light bulbs trying to chase down intermittent electrical problems. The radio would cut out, and the anti-theft system would occasionally prevent the truck from starting. A quick scan showed a dozen communication codes. The root cause? Not a bad ground, but a failing BCM. Installing a pre-programmed module like this one solved every single issue in under 10 minutes. It’s a reminder that starting with the vehicle’s ‘brain’ can save hundreds in unnecessary parts and labor.
Is Your Truck Showing These Symptoms?
A failing BCM doesn’t always throw a check engine light. Instead, watch out for these common electrical gremlins. If your truck is experiencing any of these, a new 2007-2011 Sierra 1500 BCM is the likely fix.
- ✔ Power windows, door locks, or mirrors working intermittently or not at all.
- ✔ HVAC and climate controls are unresponsive or the blower motor is erratic.
- ✔ The security or anti-theft system malfunctions, causing no-start conditions.
- ✔ Headlights, taillights, or interior lights flicker, stay on, or won’t turn on.
- ✔ The airbag warning light is illuminated, often with a DTC B1001 code.
- ✔ Unexplained battery drain or communication errors with other modules.
A Straightforward Guide to Installation
You don’t need to be a professional mechanic to handle this job. The BCM is located in an accessible spot, and the entire swap is fast and simple.
- Safety First: Always disconnect the negative terminal from your truck’s battery before working on electrical components.
- Locate the BCM: On most GM trucks of this era, you’ll find the module under the driver’s side dashboard, to the left of the steering column.
- Unplug and Unbolt: Carefully disconnect the electrical connectors. They have locking tabs, so don’t force them. Then, remove any bolts or clips holding the old module in place.
- Install the New Module: Seat the new BCM in the same position, secure it, and plug in the connectors until they click firmly into place.
- Reconnect and Test: Reconnect the battery terminal. Start your truck and test all functions—lights, locks, windows, wipers, and HVAC—to confirm the repair.
Post-Installation Note: In some cases, particularly if the airbag light was on, a ‘Setup SDM Primary Key’ procedure may be needed using a professional scan tool to sync the new BCM with the airbag system. A brake pedal position relearn might also be required for full functionality.
Will This Fit My Truck?
This module is a direct replacement for part number 20939137 and is guaranteed to fit the following vehicles. It also interchanges with part numbers 25844480, 25835966, 15943678, 22860591, and more.
SIERRA 1500 PICKUP: 2007 (New Body Style), 2008, 2009, 2010, 2011
SIERRA 2500/3500 PICKUP: 2007-2011
SIERRA DENALI: 2007-2011
YUKON / YUKON XL: 2007-2011
Chevrolet:
SILVERADO 1500 PICKUP: 2007 (New Body Style), 2008, 2009, 2010, 2011
SILVERADO 2500/3500 PICKUP: 2007-2011
AVALANCHE 1500: 2007-2011
SUBURBAN 1500/2500: 2007-2011
TAHOE: 2007-2011
Cadillac:
ESCALADE / ESV / EXT: 2007-2011
Frequently Asked Questions
Do I need to program this module?
No. We handle the programming for you. Just provide your vehicle’s VIN during checkout, and it will arrive ready to install right out of the box.
What tools are required for installation?
Typically, you only need basic hand tools like a socket wrench or nut driver to access and remove the module. No special electronic tools are required for the physical installation.
What if my airbag light is still on after installation?
This is a known GM security feature. You will need a professional-grade scan tool with BCM/special functions to perform the ‘Setup SDM Primary Key in BCM’ procedure. This syncs the airbag system to the new BCM and turns off the light.
Is there a core charge for my old part?
Absolutely not. There is no core charge on this module. You can keep your old part or dispose of it without any hassle or extra fees.
How can I be sure this is the right part for my truck?
The best way is to match the part number from your original BCM. This module replaces 20939137 and many others. If you’re unsure, check the fitment list or contact us with your VIN, and our experts will verify compatibility for you.