Abstract: Signalling apparatus for retrofitting a vehicle, such as agricultural equipment, to provide safety indicators behind the vehicle, comprises a support detachably mountable behind the vehicle, caution indicators mounted by the support, a module in electrical communication with the caution indicators and an electrical coupling for receiving turn signals from the motor vehicle and communicating the turn signals to the module. The module includes first and second electrical paths leading to the caution indicators. The second electrical path communicates the turn signals from the electrical coupling to the caution indicators. A flasher is interposed in the first electrical path for supplying a flashing signal to the caution indicators. The first electrical path communicates the flashing signal to the caution indicators when all of the turn signals from the vehicle are inactive and communicates the turn signals to the caution indicators when at least one of the turn signals is active.