Normal Operation
The TBC module receives fused battery power from central junction box (CJB) fuses 101 (30A) and 28 (10A) along circuits 50 (RD) and 298 (VT/OG), respectively. The ground path for the TBC module is along circuit 206 (WH). 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, according to the TBC gain setting, 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).