Abstract: A glow plug for a diesel engine comprises a glow plug body, and a glow rod connected to the glow plug body. The glow rod has an inner heating element connected between an engine ground and a heating element power terminal. Located on a front end surface of the glow rod is an ionization detection element. An ionization detection circuit is integrated within or near the glow plug body to connect the ionization detection element to an ionization detection collector, and communicate an ionization signal to an engine control unit via the detection collector.

Abstract: This feature of the present invention comprises a method, apparatus, and system for detecting and conditioning an ionization current signal. In one embodiment of the invention, an analog signal conditioning circuit detects and processes the ionization signal. The analog signal conditioning circuit uses a signal isolator having an input and an output, an amplifier having a first and a second input, and a first and a second output, wherein the first input operably connected to the signal isolator output, a peak detector having a first and a second input, and an output, wherein the first input is operably connected to the first output of the amplifier, and an integrator having a first and a second input, and an output, wherein the first input is operably connected to the second output of the amplifier.

Abstract: In a first embodiment, the present invention is a method of detecting an open secondary winding, including the steps of enabling an integrator, resetting the integrator, detecting an ionization current, integrating the ionization current over a spark window, comparing the integrated ionization current with a threshold, and setting an open secondary flag if the integrated ionization current is below the threshold. In another preferred embodiment, the invention is a method of detecting an open secondary winding by measuring spark duration including the steps of comparing an ionization signal with a first threshold, measuring the spark duration when the ionization signal is greater than the first threshold, comparing said spark duration with a second threshold, and setting an open secondary flag.

Abstract: In the present invention, the ionization signals from a plurality of cylinders are multiplexed together to reduce the powertrain control module pin count. For an inline internal combustion engine, the total pin count is reduced from the total number of cylinders in the engine, up to five, to one. In a preferred embodiment, the method of multiplexing ionization signals from a plurality of cylinders, consists of calculating an action period, combining the ionization signals, whereby information from said ionization signals is spaced apart by at least an action period in duration, and outputting the ionization signals, whereby no overlap of information occurs between the ionization signals.