Stop Staring at the “Service Trailer Brake System” Warning
Seeing that persistent warning light on your dash is more than just an annoyance—it’s a critical safety alert. A faulty Trailer Brake Control Module (TBCM) means you’ve lost the ability to properly control your trailer’s brakes, putting you, your cargo, and others at risk. This is especially true when hauling heavy loads with your Sierra or Silverado. This module is the direct, reliable solution to restore your truck’s essential towing capabilities and give you back the confidence you need on the road.
Common Symptoms & Your Solution
If you’re experiencing any of the issues below, a failing TBCM is the most likely culprit. This part is engineered to be the definitive fix for:
- The “Service Trailer Brake System” message on your Driver Information Center (DIC).
- No output or intermittent power to your trailer’s brakes.
- The trailer brake gain adjustment not responding.
- Diagnostic Trouble Codes (DTCs) related to the trailer brake control circuit.
Our process makes the repair simple. We take a brand new, genuine-specification GM 25788981 Trailer Brake Control Module and professionally flash it with the latest GM software, programmed specifically to your truck’s Vehicle Identification Number (VIN). This means it arrives at your door ready for a true plug-and-play installation, saving you from a costly and time-consuming trip to the dealership for programming.
Features & Benefits
- ✔ VIN-Programmed for Your Truck: We flash the module to your specific VIN before shipping. This ensures perfect communication with your truck’s other systems, eliminating the need for dealer programming.
- ✔ Restores Towing Safety: Regain full, responsive control over your trailer’s braking system for safer hauling in all conditions.
- ✔ Direct-Fit Replacement: Designed to be a perfect match for the original module on a wide range of 2007-2009 GM trucks, guaranteeing a straightforward installation.
- ✔ Eliminates Annoying Warnings: Permanently clear the “Service Trailer Brake System” message from your dashboard and drive without distractions.
- ✔ Reliable, Long-Term Performance: Built to meet or exceed original equipment standards for durability and function, giving you a lasting repair.
- ✔ Purchase with Confidence: This unit is backed by our one-year replacement warranty.
Pro-Tip From the Garage
We often see trucks where the TBCM has failed due to moisture intrusion or corrosion at the connector, especially since it’s mounted on the frame rail. When you replace your old module, take an extra minute to inspect the wiring harness connector. Clean any dirt or corrosion with a terminal cleaner and apply a small amount of dielectric grease to the seal. This simple step can prevent future communication errors and significantly extend the life of your new GM 25788981 Trailer Brake Control Module.
Frequently Asked Questions
Why is VIN programming necessary for this part?
On these GM trucks, the Trailer Brake Control Module must be programmed to the truck’s specific VIN to communicate correctly with the Body Control Module (BCM) and other vehicle systems. Without programming, the part will not function and the error message will remain. We handle this for you so it’s ready to install out of the box.
Where is this module located on my truck?
The TBCM is typically mounted to the frame rail on the driver’s side (LH side), near the rear of the truck, often close to the spare tire. It’s a black plastic box with an electrical connector.
Will this part fix the “Service Trailer Brake System” message?
Yes, in the vast majority of cases, a faulty TBCM is the direct cause of this specific warning message. Replacing it with this pre-programmed unit is the standard, correct repair for the issue.
What are the compatible part numbers?
This module is a direct replacement for part numbers 20850923, 25854535, 25788981, and 25907533. If your original module has one of these numbers, this part is a guaranteed fit.
How do I provide my VIN?
After you complete your purchase, simply send us a message with your 17-digit VIN. We cannot ship your order until we receive this information, as the programming is a critical step in the process.
Is this a difficult part to install?
For someone with basic mechanical skills, this is a relatively simple installation. It typically involves disconnecting the battery, locating and unplugging the old module, unbolting it from the frame, and then installing the new GM 25788981 Trailer Brake Control Module in reverse order. Since it’s pre-programmed, no special tools are needed.