Trailer Brake Power Control Module
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2020 GMC Yukon XL, 2020 GMC Yukon, 2020 Chevrolet Tahoe, 2020 Chevrolet Suburban, and 2020 Cadillac Escalade ESV. However, it is still accessible from the selected car via links, so may be relevant.
The K133 Trailer Brake Power Control Module (TBPM) is a solid state power switching module that supplies power to the trailer brakes at the input command duty cycle. Diagnostic messages are sent from the TBPM to the CCM on a dedicated LIN bus.