Finally Solve Your Truck’s Electrical Gremlins
If you’re dealing with bizarre electrical issues in your 2007-2011 Chevrolet Avalanche 1500, you know the frustration. One day the power windows work, the next they don’t. The security light flashes for no reason, or the HVAC system has a mind of its own. These aren’t random quirks; they’re classic signs of a failing Body Control Module (BCM), the central command center for your truck’s body electronics. This replacement BCM, part number 20939138, 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 costly trip to the dealership.
Is Your Avalanche Showing These Symptoms?
A faulty BCM can cause a cascade of confusing problems. As a technician, I’ve seen these modules cause headaches for countless owners. Here are the most common indicators that your BCM is the culprit:
- ✔ Intermittent or non-functional power windows, door locks, or interior/exterior lights.
- ✔ HVAC controls that don’t respond or a blower motor that works sporadically.
- ✔ An airbag warning light that won’t turn off, often accompanied by Diagnostic Trouble Code (DTC) B1001.
- ✔ Security system malfunctions, causing no-start conditions, stalling, or random alarms.
- ✔ A cluster of seemingly unrelated communication codes (U-codes) stored in the vehicle’s memory.
- ✔ Strange grounding issues or misfires that can’t be traced to the engine management system.
From the Diagnostic Bay: The Case of the Haunted Silverado
A customer brought in a 2010 Silverado 1500 with a laundry list of complaints: the radio display was on but produced no sound, the wipers would activate on their own, and the ‘door ajar’ warning stayed on constantly. He’d already replaced the battery and checked every fuse he could find. A scan revealed multiple loss-of-communication codes with various modules. This immediately pointed me to the BCM. Instead of spending hours chasing wires, we installed a VIN-programmed BCM. In under 15 minutes, every single issue was resolved. This is a prime example of how a single failing 2007-2011 Avalanche 1500 BCM (and its counterparts) can create widespread, phantom problems.
A Straightforward Guide to Installation
One of the biggest benefits of this module is its simple installation. You don’t need to be a master mechanic to get the job done right in your own driveway. The entire process typically takes less than 15 minutes.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before working on any electrical components.
- Locate the BCM: On most GM trucks of this era, the BCM is located under the driver’s side of the dashboard, usually to the left of the steering column.
- Disconnect and Remove: Carefully unplug the electrical connectors from the old BCM. They have locking tabs that need to be pressed to release. Once disconnected, unclip or unbolt the old module from its mounting bracket.
- Install the New Module: Seat the new, pre-programmed BCM into the mounting bracket and securely plug in all the electrical connectors. You’ll hear a click as they lock into place.
- Reconnect and Test: Reconnect the negative battery terminal. Start the vehicle and test all functions—lights, locks, windows, wipers, and HVAC—to confirm the repair was successful.
Verified Vehicle Compatibility
This module is a direct replacement for part number 20939138 and is interchangeable with many other GM part numbers, including 25844480, 25835966, 15943678, and 22860591. It is guaranteed to fit the following models:
- Chevrolet Avalanche 1500: 2007-2011
- Chevrolet Silverado 1500/2500/3500: 2007-2013
- Chevrolet Suburban 1500/2500: 2007-2011
- Chevrolet Tahoe: 2007-2011
- GMC Sierra 1500/2500/3500 & Denali: 2007-2013
- GMC Yukon & Yukon XL 1500/2500: 2007-2011
- Cadillac Escalade, ESV, EXT: 2007-2011
Note: For 2007 models, this fits the ‘new style’ with a smooth door skin. Always verify your part number or contact us with your VIN to ensure perfect fitment.
Frequently Asked Questions
Frequently Asked Questions
What does a Body Control Module (BCM) do?
The BCM acts as the central computer for your vehicle’s body-related accessories. It controls non-engine functions like power windows, locks, lights, wipers, the security system, and the climate control system, ensuring they all work together correctly.
Why is VIN programming so important?
VIN programming loads your truck’s specific software and options into the BCM. This ensures all features your vehicle was built with (like remote start, specific lighting, etc.) work perfectly out of the box. It eliminates the need for expensive dealer programming.
Is this a difficult part to replace myself?
Not at all. For most DIYers with basic tools, this is a very straightforward job that takes less than 15 minutes. The module is typically easy to access under the dashboard, and since it’s pre-programmed, it’s a simple plug-and-play swap.
What if my airbag light is on after installing the new BCM?
In some cases, a new BCM needs to be electronically ‘introduced’ to the airbag system’s computer (SDM). If the airbag light stays on, a technician will need to perform a ‘Setup SDM Primary Key in BCM’ procedure with a professional scan tool. This is a quick sync that resolves the light.
Do I need to send my old part back?
No. There is absolutely no core charge for this part. You can keep your old module without any extra fees or hassle.