Restore Your Truck’s Electrical System with a Pre-Programmed BCM
If you’re dealing with baffling electrical problems in your 2013 GMC Sierra 2500, a failing Body Control Module (BCM) is often the culprit. As the central command for your truck’s body electronics, a faulty BCM can cause a cascade of issues that are frustrating for any owner. This OEM-quality replacement, part number 20939138, is the definitive solution. We pre-program it to your truck’s specific VIN, ensuring it works right out of the box without a costly trip to the dealership for programming. Regain control over your lights, locks, windows, and HVAC system and get your Sierra back to peak operational condition.
From the Diagnostic Bay: The Ghost in the Machine
I once had a 2013 Sierra 2500 HD in my shop with the strangest symptoms. The owner complained of the radio turning off randomly, the driver’s side window not working intermittently, and the security light flashing, preventing the truck from starting. He had already replaced the battery and checked the alternator. After hooking up my scanner, I found a slew of communication error codes (U-codes) pointing to the BCM. A poor internal ground within the original module was causing these ‘ghost’ issues. Installing a VIN-programmed BCM like this one not only fixed all the symptoms instantly but also saved the customer from chasing down endless wiring problems. This is a common failure point I’ve seen on hundreds of these GMT900 platform trucks.
Is Your Sierra 2500 Exhibiting These Electrical Faults?
A failing BCM doesn’t always throw an obvious check engine light. Instead, it manifests as a collection of annoying and often unpredictable electrical failures. If your truck is showing these signs, it’s time to test and likely replace your Body Control Module.
- ✔ The security or anti-theft system light is on, causing no-start conditions.
- ✔ Power windows, door locks, or interior/exterior lights operate erratically or not at all.
- ✔ HVAC controls are unresponsive, or the blower motor works intermittently.
- ✔ The dashboard displays false warnings or error messages.
- ✔ You’re seeing diagnostic trouble codes (DTCs) like B1001 (SDM Mismatch) after an airbag light appears.
- ✔ Unexplained battery drain when the vehicle is off.
A Straightforward Guide to Your BCM Installation
For the confident DIYer or professional mechanic, replacing the BCM is a quick job that requires basic tools and less than 15 minutes of your time. This module is designed for a direct fit, making the process simple.
- Safety First: Always disconnect the negative terminal from your truck’s battery to prevent any electrical shorts.
- Locate the BCM: On most GM trucks of this era, the BCM is located under the driver’s side of the dashboard, near the steering column. It’s a black box with several large wiring harness connectors.
- Remove the Old Module: Carefully unplug the electrical connectors. They have locking tabs that need to be depressed. Once unplugged, unclip or unbolt the module from its mounting bracket.
- Install the New BCM: Secure the new, VIN-programmed BCM onto the mounting bracket and firmly reconnect all wiring harnesses. Ensure each plug clicks securely into place.
- Reconnect and Test: Reconnect the negative battery terminal. Start the vehicle and test all functions: lights, wipers, power windows, door locks, and HVAC to confirm the repair was successful.
Important Note: While this module is plug-and-play for most functions, if you have an active airbag light with code B1001, a post-install ‘Setup SDM Primary Key’ procedure may be needed using a bi-directional scan tool. Also, a Brake Pedal Position Relearn might be required on certain models.
Guaranteed Fitment for Your GM Truck or SUV
This Body Control Module is a direct replacement for part number 20939138 and is interchangeable with several other part numbers, including 25844480, 25971917, 22860591, and more. It is confirmed to fit the following vehicles:
ESCALADE 07-11
ESCALADE ESV 07-11
ESCALADE EXT 07-11
SIERRA 1500 PICKUP 07-11
SIERRA 2500 PICKUP 07-13
SIERRA 3500 PICKUP 07-13
SIERRA DENALI 07-10
SIERRA DENALI 1500 11
SIERRA DENALI 2500 11-13
SIERRA DENALI 3500 11-13
SILVERADO 1500 PICKUP 07-11
SILVERADO 2500 PICKUP 07-13
SILVERADO 3500 PICKUP 07-13
SUBURBAN 1500 07-11
SUBURBAN 2500 07-11
TAHOE 07-11
YUKON 07-11
YUKON XL 1500 07-11
YUKON XL 2500 07-11
Frequently Asked Questions
Frequently Asked Questions
What does VIN programming do for me?
VIN programming configures the module with your truck’s specific software and options package from the factory. This makes the installation plug-and-play, avoiding the need for expensive dealership tools to make it work.
Do I need to return my old BCM?
No, there is no core charge for this part. You can keep your old module without any extra fees or hassle.
My airbag light is on. Will this fix it?
If the airbag light is caused by a BCM failure (often DTC B1001), this module will resolve the root cause. However, you may need a professional scan tool to perform a ‘Setup SDM Primary Key in BCM’ procedure to clear the light after installation.
Is this a difficult part to install myself?
For someone with basic mechanical skills, this is a very straightforward repair. It’s typically held in by clips or a couple of bolts under the dash and requires no special tools for the physical swap.
How do I know for sure my BCM is the problem?
The best way to confirm is with a professional diagnostic scan. A failing BCM will often set communication codes (U-codes) or specific body-related codes (B-codes). The symptoms listed above are also strong indicators of a BCM issue.