Abstract: An automotive system has a primary control module, such as an engine control module (ECM) configured for connection to a malfunction indicator lamp (MIL), and a secondary control module, such as a transmission control module (TCM), each in communication with each other over a bus. Each control module includes a respective diagnostic data status record. Each record includes a pending fault field, a confirmed fault field and an MIL control status field. An improved method for synchronizing the diagnostic data contained in the respective status records includes an extended status signal set that is used to communicate over the bus. The set includes a diagnostic testing complete signal, a fault present signal and a MIL request signal indicative of a request to illuminate the MIL. Logic in the receiving control module (ECM) interprets the extended status signal set to properly synchronize its diagnostic data status record with the TCM's, including both pending and confirmed faults.

Abstract: A first method is suitable for vehicles having an ambient temperature sensor and employs an estimation model configured to estimate a minimum start-up engine coolant temperature (SUECT) if the engine block heater was operated during the previous soak period. A measured SUECT is then compared to estimated minimum SUECT from the model, and if it is higher, then the diagnostic logic concludes that the engine block heater was operated during the soak period, and disables the reporting its test results. A second method is suitable for vehicles without an ambient (soak) temperature sensor employs an alternative approach. Predetermined data based on actual vehicle testing over a wide range of conditions is stored in a data structure. The data describe respective minimum and maximum start-up IAT thresholds versus SUECT. The thresholds are spaced apart to define a start-up IAT window in between. In other words, the window is bounded by minimum and maximum start-up IAT thresholds.

Abstract: A system and method for evaluating the integrity of a leak detection test for a purge valve of a fuel system in a vehicle reduces or eliminates false failures. The method is executed on an engine control module (ECM) and is configured to determine when vehicle soak conditions meet first criteria conducive to fuel vapor condensation in the fuel tank. The first criteria include a predetermined temperature drop in ambient air temperature between successive drive cycles. The ECM is further configured to determine when a vehicle maneuver meets second criteria indicative of the capability of the maneuver to initiate fuel slosh in the fuel tank, to thereby establish a trigger event. The ECM is further configured to determine, after the trigger event, the maximum slope of a fuel tank vacuum increase. The ECM is still further configured to produce a slope ratio as a function of the maximum vacuum increase slope and a reference vacuum slope corresponding to a slope that is unaffected by any slosh/condensation events.

Abstract: In a carburetor, an electromagnet energized according to a pulse width modulated duty cycle has a stationary pole member which drives a pair of permanently magnetic valves against the bias of a pair of permanently magnetic discs to control fuel flow through a main metering orifice and air flow through an idle air bleed.

Abstract: A system for positioning an engine control element has a sensor measuring a value corresponding to the actual position of the element, a reference providing a command value establishing the proper position for the element, an electronic control which compares the measured value with the command value, and an actuator including a fluid pressure responsive motor for moving the element and a pressure regulator directed by the electronic control to regulate the fluid pressure delivered to the motor and cause the motor to move the control element to the proper position. The pressure regulator has a coil energized by the electronic control and a valve member which floats between a regulated-pressure-reducing bias caused by the magnetic flux created in the coil and a regulated-pressure-increasing bias caused by a varying but uncontrolled pressure differential.