Abstract: Disclosed is an ignition signal control apparatus and method for a distributorless ignition system of the type having a sensing circuit which generates at least one reference signal which may be used to periodically indicate when ignition spark plugs should be fired, and at least one identifier signal determinative of the engine's crank angle position to identify the spark plug firing sequence. One aspect of the invention includes detecting that a transition in the identifier signal has not occurred, and generating a replacement signal independent of the crank angle position, to select one or more of the spark plugs to fire.

Abstract: An invention for detecting loss of input signals to a distributorless ignition system (17) and for providing appropriate responses upon detecting fault conditions. If a SPOUT signal (31) faults low, the invention will control ignition sequence through use of a CID signal (14), and the CID signal (14) and a PIP signal (13) will be operably substituted for the missing SPOUT signal (31) to assure timely ignition. If the SPOUT signal (31) faults high, the CID signal (14) will again be utilized to sequence the firing sequence and the PIP signal (13) will be substituted for the SPOUT signal (31). If the CID signal (14) faults, firing sequence will continue to be incremented in response to receipt of the SPOUT signal (31). In addition, the invention provides for recovery of normal operation should any of the above fault conditions prove to be transient.