Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Trailer Brake Control Function
The gain buttons set the TBM for specific towing conditions such as trailer load, vehicle load, road conditions and weather. The gain is normally set to provide maximum trailer braking while maintaining trailer stability. For information on setting the trailer brake gain, refer to the Owner's Literature.
The manual slider switch on the TBM activates the trailer brakes independently from the vehicle brakes. The manual slider is used in conjunction with the gain buttons to adjust and set the trailer brakes. When the manual slider switch is activated with a trailer connected to the vehicle, the trailer stoplamps and the vehicle stoplamps illuminate.
Once the driver sets the desired gain, the TBM monitors the HS-CAN and FD-CAN messages from the PCM, ABS module and BCM as well as the manual slider switch input to determine if trailer braking is necessary. If trailer braking is necessary, the TBM sends a PWM signal to the trailer to activate the trailer brakes.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.