Restore Full Towing Control to Your GM Truck
Regain the confidence and safety of your truck’s integrated towing system with this genuine GM Trailer Brake Control Module (TBCM), part number 20791897. If you’re seeing the dreaded “Service Trailer Brake System” message on your driver information center, or experiencing intermittent or non-functional trailer brakes, a failing TBCM is the most common culprit. This crucial component is the brain behind your trailer’s braking, interpreting signals from your truck’s computer and your manual input to apply the trailer brakes smoothly and effectively. Driving without a properly functioning module is not only frustrating but a significant safety hazard, especially when hauling heavy loads.
From the Diagnostic Bay
We had a customer with a 2011 Silverado 3500 who was at his wit’s end. He was getting constant “Trailer Disconnected” alerts, even when his fifth wheel was securely hitched. He’d spent a fortune replacing the 7-pin connector on his truck, the pigtail on his trailer, and even had a trailer shop rewire part of the trailer itself. The problem persisted. When he brought it to us, a quick scan showed communication fault codes with the TBCM. We inspected the module on the driver-side frame rail and found the housing compromised, with clear signs of water intrusion and corrosion on the connector. After installing a VIN-programmed TBCM like this one, all the phantom alerts vanished and his trailer brakes worked perfectly. The issue was never the wiring; it was the module all along.
Common Symptoms of a Failing TBCM
- ✔ Constant “Service Trailer Brake System” warning light on your dashboard.
- ✔ The manual trailer brake gain control or slide lever does not respond.
- ✔ No power output to the trailer’s electric brakes, confirmed with a multimeter.
- ✔ Intermittent “Trailer Connected” and “Trailer Disconnected” messages, with or without a trailer attached.
- ✔ Stored diagnostic trouble codes (DTCs) such as C1510, C1515, or U0137 pointing to the TBCM.
- ✔ Inconsistent or jerky trailer brake application.
The Direct-Fit Solution: Your Pre-Programmed 2011-2012 Sierra 2500 TBCM
Don’t settle for a generic part that requires an expensive trip to the dealership for calibration. We provide a complete, ready-to-install solution. When you purchase this module, you provide us with your vehicle’s VIN. Our technicians will then program the module with the latest official GM software specific to your truck’s exact configuration. This ensures seamless communication with your truck’s other control modules, like the BCM and ECM, for flawless operation right out of the box. It’s a true plug-and-play fix that saves you time, money, and the headache of a dealership appointment.
Guaranteed Fitment for Your Vehicle
This module is a direct replacement for part number 20791897 and is guaranteed to fit the following vehicles:
- 2011-2012 GMC Sierra 2500 / 3500 Pickup
- 2011-2012 GMC Sierra Denali 2500 / 3500
- 2011-2012 Chevrolet Silverado 2500 / 3500 Pickup
- 2011-2012 Chevrolet Suburban 2500
- 2011-2012 GMC Yukon XL 2500
Frequently Asked Questions
Why do I need to provide my VIN?
Your truck’s VIN allows us to program the Trailer Brake Control Module with the precise software and calibrations for your specific vehicle options. This ensures it communicates correctly with the rest of your truck’s systems, making the installation truly plug-and-play without needing a dealer visit.
Is this part difficult to install?
No, installation is straightforward for someone with basic mechanical skills. The module is typically located on the driver’s side frame rail, near the rear of the truck. It involves disconnecting the electrical connector and removing a few bolts. Since our module comes pre-programmed, no further electronic work is needed after installation.
Will this fix the “Service Trailer Brake System” message?
In the vast majority of cases, yes. The “Service Trailer Brake System” message is the most common indicator of a failed TBCM. This module is designed to resolve that specific issue, provided the fault lies with the module itself and not wiring or the trailer.
Where is the TBCM located on my truck?
For Sierra and Silverado pickups, the module is mounted to the inside of the left-hand (driver’s side) frame rail, typically ahead of the rear axle. For Suburban 2500 and Yukon XL 2500 models, it is located in a similar position, around the middle of the left-hand frame rail.
Is this a genuine GM part?
Yes, this is a genuine OEM-spec part that is programmed with official GM software. It is designed to meet or exceed the original factory specifications for performance and longevity.