Restore Towing Confidence in Your GM Heavy-Duty Vehicle
As a technician with over two decades of experience, I’ve seen the frustration firsthand: you hook up your trailer, start your truck, and are immediately greeted by the dreaded “Service Trailer Brake System” message. This isn’t just an annoying light; it’s a critical safety warning that your trailer’s brakes may not function when you need them most. The culprit is often a failed Trailer Brake Control Module (TBCM), especially on these GM HD trucks where it’s mounted on the frame, exposed to years of road salt, water, and vibration.
Don’t risk your safety or pay exorbitant dealership prices for a replacement and programming. This genuine GM Trailer Brake Control Module, part number 20964299, is the definitive solution. We take the hassle out of the repair by professionally programming the module to your vehicle’s specific VIN before it ships. This means it arrives at your door ready for a direct, plug-and-play installation. You get a fully functional, reliable TBCM with the latest GM software updates, without the need for an expensive trip to the dealer. This is the same high-quality part you’d get from the dealership, but with the programming already done for you.
From the Diagnostic Bay
A customer brought in his 2013 Silverado 2500 last month, completely frustrated. His dash displayed the ‘Service Trailer Brake System’ warning constantly, and his new fifth-wheel trailer’s brakes wouldn’t engage at all. He’d already replaced the 7-pin connector, thinking it was a simple wiring issue. After a quick scan, I found a ‘No Communication with TBCM’ code. I put the truck on the lift and found the module on the driver’s side frame rail. The connectors were green with corrosion and the module’s casing was swollen—a classic sign of internal water damage. We replaced it with one of our pre-programmed modules. The entire job took less than 30 minutes, the codes cleared, and he was back on the road, towing safely. This is a common failure, and a pre-flashed module is the fastest, most reliable fix.
Is Your Truck Showing These Symptoms?
A failing TBCM can cause a range of issues that compromise your towing safety. If you’re experiencing any of the following, it’s time for a replacement:
- ✔ “Service Trailer Brake System” message on the Driver Information Center (DIC).
- ✔ Trailer brakes not applying or applying erratically.
- ✔ Inability to adjust trailer gain using the in-cab controller.
- ✔ Diagnostic Trouble Codes (DTCs) related to the TBCM or trailer brake circuit.
- ✔ The trailer disconnects and reconnects randomly on the DIC display.
A Straightforward Guide to Installation
Replacing your 2013 Suburban 2500 TBCM is a job most DIYers can handle with basic tools. Since we program it beforehand, no special scanners are needed.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts.
- Locate the Module: On the Suburban 2500 and Yukon XL 2500, the TBCM is typically located on the driver’s side frame rail, about midway down the vehicle. On Sierra and Silverado pickups, it’s on the driver’s side rear frame, near the spare tire.
- Disconnect and Remove: Carefully unplug the electrical connectors from the old module. Press the release tabs firmly. Then, unbolt the module from the frame. These bolts may be rusty, so have some penetrating oil handy.
- Install the New Module: Bolt the new, pre-programmed module into the original location. Ensure it is mounted securely.
- Reconnect and Test: Plug the electrical connectors into the new TBCM until they click into place. Reconnect the battery terminal. Start the vehicle and verify that the “Service Trailer Brake System” message is gone.
Guaranteed Fitment for Your GM HD Vehicle
This module is a direct-fit replacement for several GM heavy-duty trucks and SUVs. Please verify your vehicle is on the list below. This part is a direct replacement for part numbers 20964299 and 20850923.
- 2013-2014 GMC Sierra 2500/3500 Pickup (Towing Control; LH rear frame)
- 2013-2014 GMC Sierra Denali 2500/3500 (Towing Control; LH rear frame)
- 2013-2014 Chevrolet Silverado 2500/3500 Pickup (Towing Control; LH rear frame)
- 2013 Chevrolet Suburban 2500 (Towing Control; LH middle of frame)
- 2013 GMC Yukon XL 2500 (Towing Control; LH middle of frame)
Frequently Asked Questions
Do I need to do any programming after I receive this module?
No. We program the module to your vehicle’s VIN before shipping. It arrives ready for installation with no further programming required. Just plug it in and you’re ready to go.
How do I provide my VIN?
After you complete your purchase, you will need to send us your 17-digit Vehicle Identification Number (VIN). We cannot ship the part until we receive your VIN to perform the programming service.
Is this a genuine GM part?
Yes, this is a genuine GM part, ensuring perfect fitment and function. We simply provide the essential programming service that dealerships would typically perform.
Where is the TBCM located on my 2013 Suburban 2500?
The Trailer Brake Control Module is mounted to the frame on the driver’s side (LH), located roughly in the middle of the vehicle’s length.
What is the difference between part numbers 20964299 and 20850923?
Part number 20964299 is the later, superseding part number for 20850923. They are fully interchangeable, and we supply the most current version available with the latest software updates from GM.