Restore Towing Confidence and Clear Annoying Dash Warnings
If you’re staring at the dreaded “Service Trailer Brake System” message on your dash, you know the frustration. It’s more than just an alert; it’s a sign that your truck’s most critical towing safety feature is compromised. As a technician with over two decades of experience, I’ve seen firsthand how a faulty Trailer Brake Control Module (TBCM) can turn a routine haul into a stressful, unsafe situation. This module is the brain behind your trailer’s brakes, and when it fails, you lose that essential, synchronized stopping power. Don’t risk your safety or your cargo over a malfunctioning part.
This is your direct-fit, reliable solution. We offer a genuine replacement Trailer Brake Control Module, part number 25854535, that arrives at your door ready for installation. The biggest hurdle with electronic modules is the need for expensive dealership programming—we eliminate that completely. Before we ship, we flash the module with the very latest GM software updates, precisely matched to your truck using the Vehicle Identification Number (VIN) you provide. This ensures perfect communication with your truck’s other systems and a seamless, plug-and-play installation. This isn’t just a replacement; it’s a restoration of your truck’s factory towing capability.
Real-World Repair Story
Real-World Repair Story
A customer brought in his ’08 Sierra 2500, frustrated with an intermittent “Service Trailer Brake” light and no output to his fifth-wheel’s brakes. He’d already spent money replacing the trailer-side wiring. My scan tool showed a U0100 (Lost Communication with ECM/PCM) and a C0299 (Brake Booster Performance) that was a ghost code. The real culprit, which I’ve seen dozens of times, was internal failure in the TBCM. Water intrusion and vibration at its mounting location on the rear frame are common killers. We installed a VIN-programmed module, and in 15 minutes, the codes were gone and his trailer brakes were working perfectly. He saved hours of diagnostic guesswork and the high cost of a dealer visit.
Is Your Truck Showing These Symptoms?
A failing TBCM often gives clear warning signs. If you’re experiencing any of the following, this module is the likely solution for your 2007-2009 Silverado 2500 TBCM issues:
- ✔ Persistent “Service Trailer Brake System” message on the Driver Information Center (DIC).
- ✔ No power output to the trailer brakes when the manual slide or brake pedal is applied.
- ✔ Trailer brakes lock up or apply erratically and without driver input.
- ✔ The module fails to recognize that a trailer is connected.
- ✔ Diagnostic Trouble Codes (DTCs) such as C0299 or communication errors related to the towing system.
A Straightforward Guide to Installation
Installing your new 2007-2009 Silverado 2500 TBCM is a job most DIYers can handle with basic tools. Since we’ve pre-programmed it to your VIN, no further electronic work is needed.
- Safety First: Disconnect the negative terminal from your truck’s battery to prevent any electrical shorts.
- Locate the Module: Find the old TBCM. On these GM trucks, it’s typically mounted to the inside of the driver-side frame rail, roughly below the driver’s door or bed area.
- Disconnect and Remove: Unplug the electrical connectors. Be gentle with the locking tabs, as they can become brittle over time. Then, unbolt the module from the frame.
- Mount the New Module: Bolt the new, pre-programmed TBCM into the same location.
- Reconnect and Secure: Plug the electrical connectors firmly into the new module. You should hear a click as they lock into place.
- Final Step: Reconnect the negative battery terminal. Start the truck and verify that the “Service Trailer Brake System” message is gone.
Verified Vehicle Compatibility
This module is a guaranteed fit for the following vehicles equipped with the factory towing control option. It is a direct replacement for part numbers 20850923, 25854535, 25788981, and 25907533.
- 2007-2009 Chevrolet Silverado 2500/3500 Pickup
- 2008-2009 Chevrolet Silverado 1500 Pickup
- 2007-2009 GMC Sierra 2500/3500 Pickup
- 2008-2009 GMC Sierra 1500 Pickup
- 2008-2009 GMC Sierra Denali
Frequently Asked Questions
Real-World Repair Story
A customer brought in his ’08 Sierra 2500, frustrated with an intermittent “Service Trailer Brake” light and no output to his fifth-wheel’s brakes. He’d already spent money replacing the trailer-side wiring. My scan tool showed a U0100 (Lost Communication with ECM/PCM) and a C0299 (Brake Booster Performance) that was a ghost code. The real culprit, which I’ve seen dozens of times, was internal failure in the TBCM. Water intrusion and vibration at its mounting location on the rear frame are common killers. We installed a VIN-programmed module, and in 15 minutes, the codes were gone and his trailer brakes were working perfectly. He saved hours of diagnostic guesswork and the high cost of a dealer visit.