An oil pressure switch, which is connected in an oil path of a piston oil cooling jet to diagnose oil pressure, includes an upper body and a lower body, in which a plunger vertically moves according to oil pressure; a fixing plate that is disposed between the upper body and the lower body; a moving plate that selectively contacts a fixing plate according to movement of the plunger; a spring that generates an elastic force in a direction in which the moving plate selectively contacts the fixing plate; an output terminal that outputs an output signal according to contact between the moving plate and the fixing plate; and a parallel resistor that is electrically connected with the output terminal and electrically connected with a control resistor of a controller.

An estimation unit estimates a fuel pressure on a discharge side of a high-pressure pump based on an amount of fuel injection with a fuel injection valve from a time point at which a detected fuel pressure changes from a higher status than a first pressure to a lower status, assuming that the fuel has not been discharged with the high-pressure pump. The determination unit determines that a relief valve is in an open status based on a dropping mode of the estimated fuel pressure and a dropping mode of the detected fuel pressure.

An estimation unit estimates a fuel pressure on a discharge side of a high-pressure pump based on an amount of fuel injection with a fuel injection valve from a time point at which a detected fuel pressure changes from a higher status than a first pressure to a lower status, assuming that the fuel has not been discharged with the high-pressure pump. The determination unit determines that a relief valve is in an open status based on a dropping mode of the estimated fuel pressure and a dropping mode of the detected fuel pressure.

If the operator attempts to stop the engine incorrectly it may destroy the alternator diodes and the battery. A protective circuit is disclosed which keeps the alternator field connected to the battery until a signal such as the engine-oil pressure reports that the engine has stopped. The protective circuit is small and connects to existing engine control panels; it may also test itself without any risk of damaging the alternator or the battery.

If the operator attempts to stop the engine incorrectly it may destroy the alternator diodes and the battery. A protective circuit is disclosed which keeps the alternator field connected to the battery until a signal such as the engine-oil pressure reports that the engine has stopped. The protective circuit is small and connects to existing engine control panels; it may also test itself without any risk of damaging the alternator or the battery.

A resonant sensor probe assembly includes a substrate formed from one or more dielectric materials and free-standing electrodes coupled with the substrate. The free-standing electrodes are configured to be placed into the fluid and to generate an electric field between the free-standing electrodes. A controller measures an impedance response of the sensor to the fluid between the electrodes to determine an aging effect of the sensor.

A resonant sensor probe assembly includes a substrate formed from one or more dielectric materials and free-standing electrodes coupled with the substrate. The free-standing electrodes are configured to be placed into the fluid and to generate an electric field between the free-standing electrodes. A controller measures an impedance response of the sensor to the fluid between the electrodes to determine an aging effect of the sensor.

An evaporation gas active purge system may include a purge line of connecting a canister for absorbing an evaporation gas of a fuel tank to an intake pipe; a purge pump mounted on the purge line; a purge valve mounted on the purge line to be disposed between the purge pump and the intake pipe; a pressure sensor mounted on the purge line to be disposed between the purge pump and the purge valve; and a control unit of receiving a signal from the pressure sensor, and transmitting an operating signal to the purge pump and the purge valve, wherein the control unit controls the purge pump and the purge valve by an engine condition and a vehicle speed.

An evaporation gas active purge system may include a purge line of connecting a canister for absorbing an evaporation gas of a fuel tank to an intake pipe; a purge pump mounted on the purge line; a purge valve mounted on the purge line to be disposed between the purge pump and the intake pipe; a pressure sensor mounted on the purge line to be disposed between the purge pump and the purge valve; and a control unit of receiving a signal from the pressure sensor, and transmitting an operating signal to the purge pump and the purge valve, wherein the control unit controls the purge pump and the purge valve by an engine condition and a vehicle speed.

A device and a method for diagnosing a positive crankcase ventilation (PCV) breather line. The device includes: a crankcase pressure sensor that is installed on the PCV breather line including a front end connected to an intake line and a rear end connected to a crankcase and detects a pressure inside the crankcase; and a processor that diagnoses an abnormality of the PCV breather line based on the pressure of the crankcase.