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Home >> Ford >> 2019 >> Expedition Limited, 4WD >> Repair and Diagnosis (Single Page) >> Brakes >> Mechanical - Hydraulic >> Auxiliary Brake System >> Description And Operation >> Auxiliary Brake System - Vehicles With: Trailer Brake Control - System Operation and Component Description >> System Operation >> Trailer Brake Control Function >> Notes
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Trailer Brake Control Function: Notes

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. Activating the manual slider switch without a trailer connected to the vehicle still illuminates the vehicle stoplamps.

Once the driver sets the desired gain, the TBM monitors the HS-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.