A control system controls the vehicle having turn signal lights mounted on both sides of the vehicle in response to deflection of a manually operated turn signal. The control system includes a control unit which senses vehicle speed and automatically interrupts a flashing mode after a flashing duration which is dependent upon the sensed vehicle speed. The turn signal control unit shuts off the flashing mode in response to deflection of the turn signal lever only for a brief time period and enables the flashing mode in response to deflection of the turn signal lever for a period of time which is longer than a pre-set time period. The control unit prevents cancellation of the flashing mode in response to a repeat deflection of the turn signal lever only for the brief time period. The control unit also cancels a first flashing mode associated with deflection of the turn signal lever in a first direction and enables a second flashing mode associated with deflection of the turn signal lever in a second direction in response to brief deflection of the turn signal lever in a second deflection direction. The control unit maintains operation of the flashing mode in response to deflection of the lever for a period of time longer than a pre-set time period.