A remote control system which includes (a) a receiver unit adapted to be fixedly mounted on a motor vehicle leaving at least one door lock with a first locked condition and a second unlocked condition and having circuitry for receiving a coded signal including a code portion of binary bits, memory circuitry for storing a first code of binary bits, means for comparing the code portion of a received coded signal with the first code and circuitry for shifting the controlled device to one of the conditions upon the comparison match between the code portion of a received signal and the stored first code and (b) a transmitting unit for transmitting the stored second code of binary bits when the door lock is to be shifted into one of its conditions. In this system the invention involves the improvement wherein the coding of the second code set into the transmitter is a unique group of binary bits and the receiver unit includes a field programming arrangement for setting the first code of the receiver unit to the unique group of binary bits in the transmitting unit by using the signal from the transmitting unit as received by the receiver unit. In accordance with this improvement, the first code of the receiver unit is set to the second code of the transmitting unit in the field and may be changed from one code to another code upon authorized use of a second transmitting unit having its own unique code.