An electrical connector having means providing a signal when the connector members are fully engaged. The coupling nut on one connector member carries a detent pin which engages a mating recess in the shell of the connector member when the member is fully coupled to its mating connector member. When the detent pin engages the recess, an electrical indicator circuit is closed providing a signal that the connector members are mated. A releasable lock ring is also provided on the coupling nut which maintains the detent pin engaged with the recess.