Gm Global Technolgoy Operations, Inc.

Randolph K-k Chiu

William Thomas Phillips, Jr

Keith A Penney

Donald Robert Van Uum

Francis G Cox

Douglas A Stiff

A spark plug is provided which is suitable for use in a spark ignition system for an internal combustion engine. The spark plug is equipped with a specially configured firing tip on each of its electrodes for the purpose of minimizing the demand voltage of the spark plug, as well as extending the life of the spark plug by maximizing the time over which the demand voltage will remain within an acceptable level. For this purpose, the firing tips are configured such that their firing surfaces include at least three edges and three corners which serve as arc initiation sites of a relatively low resistance arc path between the electrodes.

High efficiency, extended life spark plug having shaped firing tips

An apparatus for providing a service reminder when a vehicle has accumulated a predetermined mileage comprises a potentiometer operated by the highest order number wheel of the vehicle odometer to provide an output voltage which changes incrementally with each indexing motion of that number wheel. An electrical detector responsive to the potentiometer output energizes a signal lamp when the output reaches a voltage in a predetermined range representing a desired service interval. An electrical connector in circuit with the potentiometer can be disconnected to change the potentiometer voltage to a value outside the predetermined range to allow the service reminder circuit to turn off the indicator lamp when the indicated service has been performed. The apparatus is adapted to operate in conjunction with an electronic engine control module which can be programmed to detect the predetermined value of the potentiometer output and to operate a signal lamp. The potentiometer output in addition provides information to the electronic control module on the accumulated mileage of the vehicle.

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Davison, MI, United States of America

Randolph K-k Chiu