Hill start assist system

A method of activating a hill start assist function in a vehicle comprising:

• a transmission electronic control unit (T-ECU) instructing an anti lock braking system electronic control unit (ABS ECU) to activate the hill start assist function;
• the ABS ECU transmitting an electrical signal to a solenoid valve;
• the solenoid valve delivering air from a pressure reduction valve to each of a double check valve, a supply line of a tractor protection valve and a control line of an inversion valve;
• the double check valve delivering air to rear axle module to activate rear brakes of the trailer;
• the tractor protection valve providing air to a supply line of the inversion valve and to glad hands associated with a trailer attached to the tractor;
• and
• the inversion valve selectively delivering air to a stop light switch based on status of a foot pedal.