Normal Operation

WARNING: This page is about a different car, the 2005 Ford Pickup, 2005 Ford F550 Super Duty, 2005 Ford F450 Super Duty, and 2005 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

The Trailer Brake Control (TBC) uses the brake pressure transducer to determine how much force is being applied to the brake pedal. This information is used to determine how much braking force needs to be applied to the trailer. The TBC uses the Brake Pedal Position (BPP) (stoplamp) switch and the brake pressure (speed control deactivation) switch to help determine the current working condition of the transducer and the related circuits. The TBC module supplies 5 volts to the transducer along circuit 3602 (TN/YE), ground for the transducer is provided along circuit 3600 (RD/WH). The voltage returned from the transducer along circuit 3601 (WH/RD) is used by the TBC module to determine current brake pressure. Fused battery voltage is sent to the normally-open stoplamp switch from Central Junction Box (CJB) fuse 18 (20A) along circuit 10 (LG/RD). The switch is connected to the TBC , multifunction switch and the center high-mounted stoplamps by circuit 511 (LG). When the brake pedal is pressed, the switch closes and the 2 circuits are connected. This sends the fused battery voltage to the TBC , multifunction switch and center high-mounted stoplamps.The normally-closed speed control deactivation switch is hardwired to the PCM. Fused ignition switch voltage is sent to the switch from Battery Junction Box (BJB) fuse 12 (2A) along 418 (DG/YE). The switch is connected to the PCM by circuit 307 (BK/YE). When the brake pedal is pressed, the switch opens and the 2 circuits are disconnected. The PCM detects this open and sends the switch information to the TBC along the High Speed Controller Area Network (HS-CAN) bus. The voltage supply to the transducer can vary between 4.5 and 5.5 volts, lower than 4.5 or higher than 5.5 will cause DTC C2797 or C2798 to set. A short to ground or an open circuit along 3601 (WH/RD) will cause DTC C2800 or C2801 to set. If the TBC detects brake pressure with no input from the stoplamp or speed control deactivation switch, DTC C2803 will be set.