Restore Towing Safety and Confidence in Your GM Truck
As a technician with over two decades of experience, I’ve seen the frustration and safety concerns that come with a malfunctioning Trailer Brake Control Module (TBCM). That dreaded “SERVICE TRAILER BRAKE SYSTEM” message on your dash isn’t just an annoyance; it’s a critical warning that your ability to safely control a heavy trailer is compromised. This module is the brain behind your trailer’s braking system, and when it fails, you lose that essential, synchronized stopping power. This isn’t a part you can afford to ignore.
We offer a dependable and straightforward solution. This genuine GM Trailer Brake Control Module, compatible with part numbers 20850923 and 20964299, arrives at your door fully programmed to your vehicle’s specific VIN. By handling the programming with the latest GM software updates before we ship, we eliminate the most expensive and time-consuming part of the repair: a trip to the dealership. You get a part that’s ready for installation right out of the box, restoring your truck’s factory towing performance and, most importantly, your peace of mind.
From the Diagnostic Bay
A customer brought in his 2013 Silverado 2500 last month, completely frustrated. He was about to leave for a camping trip, but the “Service Trailer Brake” light was on, and the manual trailer brake slider was dead. The dealership quoted him over $600 for the part, programming, and labor. I scanned the truck and found communication loss codes pointing directly to the TBCM, which is common due to its location on the frame rail where it’s exposed to moisture and road salt. We ordered this exact pre-programmed module for him. The installation took less than 30 minutes, and because it was already flashed to his VIN, it worked perfectly the moment we connected the battery. He was back on the road to his trip the same afternoon, having saved hundreds of dollars and a major headache. This is the smart, efficient fix for this common problem.
Is Your Truck Displaying These TBCM Failure Signs?
- ✔ Persistent “SERVICE TRAILER BRAKE SYSTEM” message on the driver information center (DIC).
- ✔ Trailer brakes fail to engage when you press the brake pedal.
- ✔ The manual trailer brake controller slider or switch is unresponsive.
- ✔ Intermittent or no connection detected when a trailer is plugged in.
- ✔ Diagnostic Trouble Codes (DTCs) related to the TBCM or trailer brake circuit.
- ✔ Inconsistent or jerky trailer braking performance.
A Straightforward Guide to Installation
Replacing the TBCM is a job most DIYers can handle with basic tools. This pre-programmed 2013 Yukon XL TBCM makes the process even simpler.
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Safety First: Always disconnect the negative terminal from your truck’s battery before starting any electrical work.
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Locate the Module: On most compatible models, the TBCM is mounted to the frame rail on the driver’s side, typically under the driver’s door or further back towards the rear axle. It’s a small black box with electrical connectors.
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Disconnect and Remove: Carefully press the release tabs on the two electrical connectors and pull them straight out. Then, remove the bolts or nuts (usually 2 or 3) securing the module to the frame.
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Install the New Module: Mount your new, pre-programmed TBCM onto the frame using the original hardware. Firmly plug in the two electrical connectors until they click into place.
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Final Steps: Reconnect the negative battery terminal. Start the vehicle and check the driver information center. The “Service Trailer Brake System” message should be gone, indicating a successful installation.
Guaranteed Fitment for Your GM HD Vehicle
This module is a direct-fit replacement for the following vehicles equipped with the factory trailer brake control system. Please provide your VIN upon purchase to ensure perfect programming.
- ✔ 2013-2014 GMC Sierra 2500/3500 Pickup & Denali
- ✔ 2013-2014 Chevrolet Silverado 2500/3500 Pickup
- ✔ 2013 Chevrolet Suburban 2500
- ✔ 2013 GMC Yukon XL 2500
Frequently Asked Questions
Why do you need my VIN number?
Your vehicle’s VIN is required to load the correct, vehicle-specific software from GM onto the module. This ensures it communicates perfectly with your truck’s other computers, like the BCM and ECM, for seamless, factory-correct operation without any additional programming needed.
Is this a difficult part to install myself?
No, for most individuals with basic mechanical skills, this is a very straightforward repair. The module is typically located on the driver’s side frame rail and held on by a few bolts. Since our module comes pre-programmed, it’s a simple plug-and-play process once the old one is removed.
What does the Trailer Brake Control Module (TBCM) actually do?
The TBCM interprets the braking input from your truck and sends a proportional electrical signal to your trailer’s electric brakes. It ensures your trailer brakes at the same rate as your truck, providing stable, safe, and controlled stops when towing.
Will this fix the ‘Service Trailer Brake System’ warning on my dash?
In the vast majority of cases, yes. This warning is the most common symptom of a failed TBCM. Replacing a faulty module with this pre-programmed unit is the definitive fix for the issue.
Is this part compatible with number 20964299?
Yes, this module, part number 20850923, is a fully compatible and interchangeable replacement for part number 20964299. It will function identically once programmed to your VIN.