a brake control signal generator for generating a brake control signal that is proportional to the deceleration of a towing vehicle;

a microprocessor connected to said brake control signal generator and responsive to said brake control signal to generate an output brake actuation signal at a brake signal output pin, said output brake actuation signal varying in proportion to said brake control signal between a minimum value and a maximum value;

at least one pushbutton connected to said microprocessor, said at least one pushbutton being operative to change said minimum and maximum values of said output brake actuation signal that is generated by said microprocessor; and

a programmable current sensing power switch with temperature protection which is adapted to be connected between a power supply and a set of trailer brake coils, said power switch connected to said brake signal output pin of said microprocessor and responsive to said brake control signal to supply current to said trailer brake coils that is a function of said brake control signal, said power switch also connected by a feedback resistor to a current feedback port on said microprocessor, said power switch cooperating with said current feedback resistor to supply a current feedback signal to said microprocessor that is a function of said current being supplied to said trailer brake coils, said microprocessor being operative to monitor said current feed back signal and also being responsive to said current feedback signal exceeding a predetermined current shut down threshold to cause said power switch to change to a non-conducting state for a predetermined period of time, said power switch also being operative to change directly to a non-conducting state upon the temperature of said switch exceeding a temperature shut down threshold and to remain in said non-conducting state for a predetermined period of time.