A keyless entry system for a motor vehicle is modified to be operable when the vehicle's engine is running and the vehicle's park brake is set. Keyless entry systems conventionally include an ignition switch position signal source and a door lock module having an enable input connected to the source of the ignition position signal. The disclosure teaches connecting the output of the ignition switch position sensor to the door lock modulo enable input through the part brake lamp. The enable input to the door lock module is then connected in common with the a park brake lamp switch. When the park brake lamp switch is closed by setting the park brake and activates the park brake lamp, the ignition position feed signal on the enable input is sunk by the switch and the potential level on the enable Is reduced, enabling the door lock module to operate as though the ignition switch had been moved to off.