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 braking energy that is provided to the trailer is varied with a pulse width modulated (PWM) signal that switches between 0 volt and battery voltage, the higher the duty cycle the more braking power available. On vehicles built before March 23rd, 2005 , with the vehicle stationary and with the manual slider switch fully to the left with a gain of 10, there should be greater than 1--2 volts supplied to trailer tow C4099-3, circuit 43 (DB). On vehicles built March 23rd, 2005 and later , with the vehicle stationary and with the manual slider switch fully to the left with a gain of 10, there should be greater than 10--12 volts supplied to trailer tow C4099-3, circuit 43 (DB).

Every 4 seconds the TBC module sends a voltage pulse along circuit 43 (DB) to trailer tow C4099-3 to determine whether or not a trailer is connected to the trailer tow connector. If the TBC module receives a returning voltage, a trailer is connected, if the TBC does not receive a returning voltage, a trailer is not connected.