This reverse light switch is intended for use in the electrical system of Citroën DS and 2CV vehicles. The switch detects engagement of reverse gear and closes the circuit to the reversing lamps. This supports visibility of the vehicle during reversing. The construction is matched to installation in the existing mounting points and connections. The design is based on dimensions according to PW1 specification. The housing protects the internal contacts against external influences. The switch operates together with the wiring harness and the transmission components of the vehicle.