Restore Full Electrical Function to Your GM Truck or SUV
Are you battling a storm of strange electrical problems in your GMC Yukon XL, Chevy Silverado, or Cadillac Escalade? Intermittent wipers, flickering lights, unresponsive power windows, or a dead HVAC system are classic signs of a failing Body Control Module (BCM). The BCM acts as the central nervous system for your vehicle’s body electronics, and when it malfunctions, it can make your truck feel possessed. This genuine GM BCM, part number 20939138, is the definitive solution, arriving pre-programmed to your vehicle’s specific VIN for a true plug-and-play repair.
From the Diagnostic Bay
We had a 2008 Sierra 2500 in the shop that was driving its owner crazy. He’d replaced the battery twice and the alternator once, chasing a parasitic draw that would kill the truck if it sat for more than two days. The dash lights would sometimes flicker randomly after shutdown. After checking all the usual suspects, we traced the draw back to the BCM. It wasn’t fully going to sleep, keeping other modules awake and draining the battery. Installing a VIN-programmed BCM like this one solved the issue instantly. It’s a reminder that what looks like a charging system problem can often be a control module fault.
Common Symptoms of a Failing BCM
- ✔ Unresponsive or erratic power windows, door locks, and interior/exterior lights.
- ✔ HVAC controls not working or blower motor operating intermittently.
- ✔ Security system malfunctions, causing no-start conditions or random alarm activation.
- ✔ Airbag warning light illuminated, often with Diagnostic Trouble Code (DTC) B1001.
- ✔ Communication errors with other vehicle modules, leading to a host of confusing DTCs.
- ✔ Wipers that won’t turn on, off, or park in the correct position.
Diagnosing Your 2007-2011 Yukon XL BCM
Confirming a bad BCM is key before replacing parts. A professional scan tool can check for communication errors with the BCM and specific body-related trouble codes. A common sign is multiple, unrelated electrical failures occurring simultaneously. Before condemning your 2007-2011 Yukon XL BCM, it’s wise to check for poor ground connections (especially the main cab grounds) and test relevant fuses, as these can mimic BCM failure. However, if these check out and the symptoms above persist, the BCM is the most likely culprit.
Installation and Post-Install Procedures
Physically installing the BCM is straightforward. It’s typically located under the driver’s side dashboard, near the steering column, and held in place by a few clips or bolts. The entire swap takes just a few minutes. Because this module comes programmed to your VIN, no dealer visit is required for setup. However, please be aware of two potential post-installation steps:
- Airbag System Sync: If the airbag light remains on after installation (often with code B1001), a ‘Setup SDM Primary Key in BCM’ procedure must be performed using a high-level scan tool. This syncs the new BCM with the airbag system’s Sensing and Diagnostic Module (SDM).
- Brake Pedal Position Relearn: In some cases, a brake pedal position sensor relearn may be needed to ensure correct brake light operation and stability control function. This is also done with a diagnostic scan tool.
Frequently Asked Questions
What does a BCM do on a 2007-2011 GMC Yukon XL?
The Body Control Module (BCM) is a computer that manages and controls most of your Yukon’s non-engine related electronic systems. This includes power windows, door locks, the security system, interior and exterior lighting, wipers, and the HVAC climate control system.
Is this BCM ready to install right out of the box?
Yes. We program the module to your vehicle’s unique VIN before shipping. This ensures it communicates correctly with your truck’s other systems for a plug-and-play installation, eliminating the need for expensive dealership programming.
Where is the BCM located on a 2009 Yukon XL?
The BCM is located under the driver’s side of the dashboard, typically to the left of the steering column. It is an accessible component that can be replaced with basic hand tools.
Will this fix my airbag light with a B1001 code?
A faulty BCM is a common cause of the B1001 code. Replacing it will resolve the root cause, but you may need a professional scan tool to perform the ‘Setup SDM Primary Key in BCM’ procedure to sync the new module and clear the light.
Do I need to send my old part back?
No, there is no core charge for this part. You can keep or dispose of your old module without any hassle.