A hitch mechanism comprises an interlocking safety pin and a sleeve or other mechanism which, in a locking position, exposes a hole which is adapted to receive the safety pin. The safety pin includes an interlock to activate either an audible alarm, a visible alarm, of both. In alternative embodiment, the pin mechanism further includes means to foil a would-be thief in uncoupling the towed vehicle. In a further alternative embodiment, the safety pin includes an internal power supply to eliminate certain wired connections.