In motor vehicles, it is common practice to employ one or more door jamb switches to activate electrical circuits in response to the opening and/or closing of a door. In general practice, these switches include an element that is shifted between a first and second condition when the vehicle door is opened and closed. A spring loaded plunger extends outwardly under spring tension when the door is opened, and is depressed when the door is closed. Due to dimensional variations in the design, manufacture and assembly of motor vehicles, the distance between the inner face of a door and its matching door jamb may be different from door to door. To compensate for this condition, self-adjusting door jamb switches as shown generally in U.S. Pat. Nos. 3,249,727 and 3,251,971 have been commonly employed by the automotive industry. Also of note is U. S. patent application Ser. No. 331,123 entitled "Improved Door Jamb Switch", filed Dec. 15, 1981, now U.S. Pat. No. 4,406,935 and assigned to the assignee of the present invention. These switches have a collapsible plunger or other arrangement which self-adjusts upon the initial closing of the door against the jamb after the switch has been installed. Thereafter, the switch operates in accordance with this initial adjustment. Generally, in these self-adjusting door jamb switches the plunger is adapted to reciprocate longitudinally in a mounting sleeve fixed onto the door jamb. The switch has a first contact assembly mounted to the sleeve, and a second contact assembly mounted to the reciprocating plunger. In the typical case, when the plunger is in its extended, door opened, position, electrical contacts on the two contact assemblies close, and when the plunger is in its depressed, door closed, position, the electrical contacts open.
Although self-adjusting door jamb switches have been known in the past, the self-adjusting aspect of the switch has been in the longitudinal adjustment of the plunger movement or extension within the sleeve. This adjustment, however, does not assure that the electrical contact surfaces of the switch are in good alignment. In the past, fairly close tolerances were required for individual parts of the switch in order to obtain good contact alignment. This added to the time and cost required to produce and inspect the individual parts and the switch assembly itself. Even then, contact alignment was not always adequate. In such cases, where contact alignment was less than optimum, the switches might fail prematurely due to wear and/or arcing due to poor surface contact. Also, as is known in the art of electrical switches, the current carrying capacity or rating of a switch can be adversely affected by poor alignment of the contact surface. Ultimately, without close tolerances on individual parts of the prior art switches, they might never function properly at all in some cases.