Abstract:
A fault clearing system and method for an engine control system includes a plurality of processor modules to control and monitor the engine and set a plurality of faults. The plurality of processor modules includes an electronic throttle control (ETC) module to control and monitor a throttle of the engine, and a plurality of engine sensors and ETC sensors. An ETC diagnostic module monitors the ETC sensors and engine sensors, with the ETC diagnostic module setting a low voltage induced fault. The ETC diagnostic module will also enter one of a plurality of low voltage states in response to the low voltage induced fault. The ETC diagnostic module selectively controls the ETC module and selectively clears the faults in the ETC module and plurality of processor modules upon entry into one of the low voltage states.

Description:
FIELD 
     The present disclosure relates to engine control systems, and more particularly to electronic throttle control diagnostic fault clearing for transient or temporary low voltage conditions. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     Traditionally, automotive vehicles include multiple systems that regulate overall operation of the vehicle. For example, the vehicle includes a powerplant (e.g., an internal combustion engine) that generates drive torque, an energy storage device (e.g., battery pack) that provides electrical energy, a transmission that distributes the drive torque to drive wheels and various other systemsEach of these systems requires an associated control module or modules to achieve coordinated control and operation of the vehicle. These modules communicate with one another to regulate operation of the vehicle. Intra-processor communications utilize interfaces such as an Serial Peripheral Interface (SPI) or the universal asynchronous receiver/transmitter (UART), while inter-processor communications utilize a Controller Area Network (CAN) and/or Class2 Network. 
     Electronic throttle control (ETC) systems replace the mechanical accelerator pedal assemblies also used in vehiclesETC sensors take input from the driver and send it to an engine control system in real time. The engine control system modulates the air/fuel flow to the engineDirect control of the engine is shifted from the driver to the engine control system to improve efficiency. Under certain failure mode conditions, the ETC system will operate under an acceleration governing function. This limited-power mode will prevent damage to the engine. Once a vehicle has entered limited-power mode it needs to remain there until the fault has been determined and remedied. 
     Due to the increasing complexity of automotive systems and the need for subsystems such as ETC, there exists a large number of diagnostics that are required to detect failures in a very short time (&lt;200 ms) between processors. However, a number of inter and intra-processor diagnostic fault codes may be falsely set when the voltage drops in the vehicle due to the interaction between various vehicle components operating at or beyond their specified voltage rangesLow voltage conditions may result in faults that could potentially indicate a need for costly repairs. For example, the low voltage induced faults may lead to the unnecessary replacement of components when the charging system fails and/or the vehicle battery is drained, thus causing higher warranty costs and customer dissatisfaction. 
     SUMMARY 
     Accordingly, the present disclosure provides a fault clearing system and method for an engine control system. The engine control system includes a plurality of processor modules to control and monitor the engine and set a plurality of faults. The plurality of processor modules includes an electronic throttle control (ETC) module to control and monitor a throttle of the engine, and a plurality of engine sensors and ETC sensors. An ETC diagnostic module monitors the ETC sensors and engine sensors, with the ETC diagnostic module setting a low voltage induced fault. The ETC diagnostic module will also enter one of a plurality of low voltage states in response to the low voltage induced fault. The ETC diagnostic module selectively controls the ETC module and selectively clear the faults in the ETC module and plurality of processor modules upon entry into one of the low voltage states. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a schematic of a vehicle with an improved electronic throttle control system according to the present disclosure; 
         FIG. 2  is a flow chart illustrating the steps performed by the fault clearing loop of the present disclosure; 
         FIG. 3  is a flow chart illustrating the processor initialization steps performed by the fault clearing loop of the present disclosure; and 
         FIG. 4A-4C  are flow charts illustrating the steps performed by the fault clearing algorithm of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following description of the preferred embodiment is merely exemplary in nature and is in no way intended to limit the present disclosure, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements. As used herein, the term module refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, or other suitable components that provide the described functionality. 
     Referring now to  FIG. 1 , a vehicle is schematically illustrated. The vehicle  10  is driven by an engine  12  that combusts an air and fuel mixture to produce drive torque. Air is drawn into an intake manifold  14  through a throttle body  16 . The throttle  16  allows air to flow into the intake manifold  14 . The air within the intake manifold  14  is distributed to cylinders (not shown) and is mixed with fuel for combustion. 
     Overall operation of the engine is monitored and regulated by a control module, such as an ETC  18 More specifically, the ETC  18  regulates the engine  12  based on driver inputs and engine operating conditions. The driver inputs include an accelerator pedal (not shown) and/or a cruise control module  20 . An accelerator pedal position sensor  22  is responsive to a position of the accelerator pedal and generates a pedal position signal to the ETC  18 . The accelerator pedal position is indicative of a desired engine torque output from the driver. The cruise control module  20  signals desired engine torque output based on a set point set by the driver. Engine operating conditions are provided to the ETC diagnostic module  26  and other processor modules  28  by sensors such as the throttle position sensor  24  and other engine sensors supplying signals indicative of engine performance, such as vehicle speed, etc. The electrical energy supplied to the vehicle  10  is provided by a battery  30  and it&#39;s charging system  32 . 
     The ETC diagnostic module  26  provides a complex series of diagnostics that monitor the ETC&#39;s sensors and its control of engine power. The ETC diagnostic module  26  ensures proper operation of engine  12 . For example, the ETC  18  will limit engine power when the diagnostics detect a condition that could potentially harm the engine  12 . Engine control module subsystems connected through an API network, as well as other controllers or processor modules  28  connected through CAN networks, provide for the full range of vehicle management, control and diagnostics. 
     Due to the unpredictability of low voltage conditions, control modules, including the ETC  18  are affected by transient or temporary low voltage conditions. A low voltage condition is considered transient when it originates from starter motor  34  transients that cause the vehicle voltage to drop to very low values and then ramp up slowly as inertia decreases with increasing engine RPM. An example temporary low voltage condition would be a dead battery  30  or a failed charging system  32 . 
     The ETC diagnostic module  26  initializes and resets all ETC diagnostics and fail counters, as well as other subsystems that may be affected by low voltage conditions. Controller initialization is executed at engine ignition and whenever the ETC  18  needs a “running reset.” After the initialization, the ETC diagnostic module  26  executes an assortment of diagnostics, including a periodic low voltage fault clearing loop at an exemplary interval of 12.5 ms. The periodic loop that the ETC diagnostic module  26  performs within may be a synchronous processor controlled loop. This periodic interval allows continuous monitoring for vehicle low voltage conditions. The example 12.5 ms time interval allows the ETC diagnostic module  26  time to complete the full complement of diagnostic routines, commonly known as the main diagnostics for ETC  18  operation and fault detection, before the low voltage fault clearing loop starts again. 
     The fault clearing loop begins by incrementing a series of ETC diagnostic timer modules (not shown) as determined by a comparison between ETC sensors and engine sensor readings (not shown) and predefined calibration values. In a preferred embodiment, the calibration values are set at the factory while future calibration adjustments may be possible at service stations. The sensor readings supplied to the ETC  18  are also supplied to the ETC diagnostic module  26 . With the ETC diagnostic timer modules incremented, the ETC diagnostic module  26  selects from a plurality of low voltage condition states, including: a low power state, a crank transition state, a low voltage non-cranking state, and a low voltage recovery state. 
     If the vehicle is already in a limited-power mode of operation, the low voltage fault clearing loop will be suspended without clearing any low voltage induced faults. A limited-power mode occurs when one or more ETC sensors, such as the throttle position sensor  24  or the accelerator position sensor  22  has a fault. Or if the throttle body  16  has a fault. This ensures that when the engine  12  is in a power-limited mode of operation, the ETC diagnostics will not reset a diagnostic signal nor take any remedial action which could result in increased engine power. 
     During starter motor  34  crank transitions, transient voltage drops need to be handled by clearing the low voltage related ETC diagnostics but allowing the starter motor  34  to continue to start the engine  12 . This is accomplished by the ETC diagnostic module  26  determining whether vehicle  10  voltage has dropped below a calibrated lower voltage threshold, and whether the engine  12  is cranking, and if so, the ETC diagnostic module  26  setting a low voltage cranking signal to TRUE and ensuring fuel is enabled. If the fault clearing loop determines that the vehicle  10  voltage has dropped below a calibrated lower voltage threshold and the starter motor  34  is not cranking, the ETC diagnostic module&#39;s fault clearing loop will disable all diagnostics that use or monitor the low voltage active signal. In addition, the fuel will be disabled. 
     When the vehicle  10  has recovered from its low voltage condition, indicated when the measured vehicle  10  voltage rises above a calibrated upper voltage threshold, the fault clearing loop needs to return ETC diagnostics to normal. This will be accomplished once an ETC diagnostic timer module (not shown) has given processor related failures time to clear from the ETC  18 , other ECM subsystems, and other processor modules  28 . Throughout the three operating states of the fault clearing loop, selectable when the vehicle  10  is not in a limited-power mode, fault signals are cleared from the ETC  18 , its subsystems and other processor modules  28  through the use of fault clearing modules (not shown) that apply “code clears” to the ETC diagnostic module  26  and other affected processors  28 . In other words, if the vehicle  10  is not in a limited-power mode of operation, the crank transition state, low voltage non-cranking state or low voltage recovery states may be selected by the ETC diagnostic module  26 , depending on the detected condition of the vehicle  10 , to ensure that fault signals are cleared from the ETC  18 , its subsystems and other processor modules  28  through the use of fault clearing modules that apply “code clears” to the ETC diagnostic module  26  and other affected processors  28 . 
       FIG. 2  illustrates the steps performed by the fault clearing loop of the present disclosure in a flow chart. In step  200 , all controllers and diagnostic systems are reset at engine ignition and as needed as “running resets.” Continuing in step  202 , the fault clearing method is started after each periodic interval. An exemplary periodic interval is 12.5 ms. In step  204 , a plurality of timers is incremented. In step  206 , the fault clearing loop determines whether the ETC  18  is in a limited-power mode. If the ETC  18  is in a limited-power mode, the fault clearing loop is not allowed to run. If the fault clearing loop determines the engine  12  is in a limited-power mode, the loop continues with step  208 . If the fault clearing loop determines the engine  12  is not in a limited-power mode, the loop continues with step  210 . In step  208 , the ETC diagnostic module&#39;s low power state is set by not continuing with the fault clearing loop, therefore, ETC diagnostics faults are not cleared and fuel is not disabled. In step  210 , if the fault clearing loop determines that the vehicle is operating in a low voltage condition, the loop continues with step  212 . If the fault clearing loop determines the vehicle is not operating in a low voltage condition, the loop continues with step  214 . In step  212 , if the starter motor  34  is cranking, the fault clearing loop will continue with step  216 . If the starter motor  34  is NOT cranking, the fault clearing loop will continue with step  218 . 
     In step  216 , the crank transition state is set by clearing the ETC diagnostics faults and enabling fuel to start the engine  12 During the crank transition state, starter motor  34  cranking results in a vehicle  10  voltage drop that ramps up slowly as inertia decreases with increasing engine RPM. This state will clear the ETC diagnostics but allow the starter motor  34  to start the engine  12 . The crank transition state will generate a low voltage cranking signal that clears ETC diagnostics and a signal enabling the flow of fuel. After step  216  completes, the fault clearing loop continues in step  220  and ends. 
     In step  218 , the low voltage non-cranking state is setDuring the low voltage non-cranking state, once vehicle voltage drops below a calibrated low voltage threshold and the starter motor  34  is not cranking, all diagnostics are disabled that use or monitor the low voltage active signal. Further, the fuel supply is disabled. After the fault clearing loop completes step  218 , the loop continues in step  214 . 
     In step  214 , the low voltage recovery state is set. In step  214 , if the fault clearing loop determines that vehicle voltages are no longer below a calibrated voltage threshold, the ETC diagnostic module  26  will return to normal after a preset period of time to provide a hysteresis interval. In dealing with low voltage transitions, the fault clearing loop can clear processor related failures once the processor recovers from the low voltage state. Because other processor modules  28  will also set faults when the ETC  18  fails to respond, a hysteresis loop allows enough time to clear failures but not jeopardize the security of the system. After the fault clearing loop completes step  214 , the loop continues in step  220  and ends. 
       FIG. 3  provides detailed steps for controller initialization with the use of a fault clearing algorithm. In a preferred embodiment, the fault clearing algorithm is a software routine periodically executed by the ETC diagnostic module  26 . In step  300 , controller initialization begins after vehicle engine ignition and during, as required with “running resets.” In step  302 , if VeTPSR_b_PowerUpReset equals TRUE, then control continues in step  304 . If VeTPSR_b_PowerUpReset equals FALSE then control continues in step  306 . 
     In step  304 , control sets ReTPSC_b_Clear_ETC_Codes to FALSE. This signal when TRUE, indicates that the low voltage fault clearing and fuel disable logic is active. Once step  304  is completed, control continues in step  306 . 
     In step  306 , control sets the following signals and timers to 0: VeTPSC_t_DiagCodeClrActv, VeTPSC b_EngShutdown Rqst, VeTPSC_b_DisableFuel_MHC, VeTPSC_b_Clear_ETC_Codes, VeTPSC_t_StarterEngaged and VeTPSC_t_ETC_DiagMinEnbl. VeTPSC_t_DiagCodeClrActv is used to count up to a calibration threshold value and while less than calibration, code clears will be continuously (once every periodic value, here set to an exemplary 12.5 ms) applied to ETC rings (such as APSR, MCPR, TRSR and VLTR)VeTPSC_b_EngShutdownRqst is the low voltage fuel disable signal and is set to FALSE. VeTPSC_b_DisableFuel_MHC is the redundant fuel disable signal and is set to FALSE. The VeTPSC_b_Clear_ETC_Codes signal, also set to FALSE, enables the clearing of all the ETC diagnostics and fail counters. VeTPSC_t_StarterEngaged, reset to 0 seconds, is a timer that starts when the starter motor  34  is commanded onVeTPSC_t_ETC_DiagMinEnbl, also reset to 0, is a timer that sets the minimum time the ETC diagnostics are allowed to run before any low voltage ETC diagnostic module  26  faults are cleared. Once step  306  completes, controller initialization ends. 
     Referring now to  FIG. 4A , detailed steps for clearing low-voltage faults are continued. In a preferred embodiment, the fault clearing algorithm is a software routine periodically executed by the ETC diagnostic module  26 Control begins with step  400  when each periodic task loop is started. An exemplary period may be 12.5 ms. After starting the periodic task loop, control continues in step  402 . In step  402 , control determines whether vehicle  10  voltages are below calibration thresholds and if the main diagnostics run timer is less than or equal to its calibration thresholdMore particularly, whether GetPMDR_U_RunCrank, the voltage measured on the Run/Crank Ignition controller input, is GREATER THAN calibrated threshold KeTPSC_U_ECM_VoltMin, set to an exemplary value of 6.0V, which is the low voltage check to disable the fuel and starter and to clear the ETC diagnostics, OR if GetPMDR_U_PT_Relay, the undefaulted powertrain relay voltage, is GREATER THAN calibration threshold KeTPSC_U_ECM_VoltMin, also set to an exemplary value of 6.0V, which is the low voltage check to disable the fuel and starter and to clear the ETC diagnostics; AND if VeTPSC_t_ETC_DiagMinEnbl, the main diagnostics run timer, is LESS THAN OR EQUAL TO calibrated threshold KeTPSC_t_ETC_DiagMinEnbl, set to an exemplary value of 225 ms, which is the minimum time after ignition on to allow the main diagnostics to run before clearing ETC diagnostics. If step  402  is TRUE, then control continues in step  404 , if false, control continues in step  406 . 
     In step  404 , control sets timer VeTPSC_t_ETC_DiagMinEnbl, equal to its current value plus a periodic value, CfETCS_t_PeriodicA, set to an exemplary value of 12.5 ms. After step  404  is completed control continues in step  406 . 
     In step  406 , control determines whether vehicle  10  voltages are above calibration thresholdsMore particularly, whether GetPMDR_U_PT_Relay, the undefaulted powertrain relay voltage, is GREATER THAN calibration threshold KeTPSC_U_LowVoltageHysteresis, set to an exemplary value of 8.5 V, which provides a voltage stability check used in the low voltage fault clearing logic; OR if GetPMDR_U_RunCrank, the voltage measured on the Run/Crank Ignition controller input, is GREATER THAN calibration threshold KeTPSC_U_LowVoltageHysteresis. If vehicle voltages are above threshold levels, then the correction algorithm continues in step  408 , if not, control continues in step  410 . 
     In step  408 , control determines whether VeTPSC_t_LowVoltageHysteresis, the timer used for the minimum time needed for voltage to become stable above a threshold before the low voltage fault clearing request and fuel disable logic is cleared, is LESS THAN OR EQUAL TO the calibrated threshold, KeTPSC_U_LowVoltageHysteresis, set to an exemplary 500 ms, which provides a hysteresis loop for the voltage stability check used to clear low voltage induced faults. If VeTPSC_t_LowVoltageHysteresis is LESS THAN OR EQUAL TO KeTPSC_U_LowVoltageHysteresis, control continues in step  412 , if not, control continues in step  414 . 
     In step  410 , control sets VeTPSC_t_LowVoltageHysteresis to 0.VeTPSC_t_LowVoltageHysteresis is the timer providing the hysteresis loop for voltage to become stable above a threshold before the low voltage fault clearing request and fuel disable logic is cleared. After step  410  is completed, control continues in step  414 . 
     In step  412 , control sets timer VeTPSC_t_ETC_DiagMinEnbl, the timer providing for a minimum time to allow the main diagnostics to run, equal to its current value plus the periodic value, CfETCS_t_PeriodicA, set to an exemplary 12.5 ms. After step  412  is completed control continues in step  414 . 
     In step  414 , control enters the Crank Transition state. In the Crank Transition state, if control determines that the starter motor  34  is being commanded on, fuel will be enabled and the low voltage induced processor related faults will be clearedControl continues in step  414 , by executing GetSTRR_b_StrtCntrlStOn, which returns an indication of the PCM controlled commanded state of the starter output driver. If GetSTRR_b_StrtCntrlStOn is TRUE, control continues in step  416 , if FALSE control continues in step  418 . 
     In step  416 , control sets VeTPSC_t_StarterEngaged, the timer that starts when the starter is commanded on, equal to its current value plus the periodic value, CfETCS_t_PeriodicA, set to an exemplary 12.5 ms. After step  416  is completed control continues in step  420  (seen in  FIG. 4B ). 
     In step  418 , VeTPSC_t_StarterEngaged, the starter motor  34 , is set to 0. After step  418  is completed control continues in step  420  (seen in  FIG. 4B ). 
     Referring now to  FIG. 4B , detailed steps for a periodic task loop are continued. In step  420 , control determines whether vehicle  10  low-voltage, engine starter ON conditions exist, as well as whether the engine  12  is in a limited-power modeMore specifically, control determines whether the Run/Crank voltage, GetPMDR_U_RunCrank, is LESS THAN its calibrated threshold, KeTPSC_U_CrankTransition, set to an exemplary 7.0 V; AND whether the powertrain voltage, GetPMDR_U_PT_Relay, is also LESS THAN KeTPSC_U_CrankTransition; AND whether starter motor  34  timer, VeTPSC_t_StarterEngaged, is LESS THAN its calibrated threshold, KeTPSC_t_CrankTransition, set to an exemplary 15 seconds, the calibrated time where crank transition caused low voltage conditions won&#39;t set ETC diagnostic faults; AND whether GetSTRR_b_StrtCntrlStOn is TRUE, indicating the starter motor  34  is ON; AND whether the RPM of the engine, GetEPSR_n_Engine, is LESS THAN its calibrated threshold, KeTPSC_n_LowVoltageStarterDsbl, set to an exemplary 800RPM, an RPM threshold used to disable the low voltage crank fault clearing logic; AND whether ReTPSD_b_EngPowerLimited, indicating whether engine power should be limited, is equal to FALSE; AND whether ReTPSD_b_ReducedPwrActive_MCP, indicating whether the engine is in a limited-power mode, is FALSE. If step  420  is true, then control continues in step  422 . If step  420  is false, control continues in step  424 . 
     In step  422 , control determines whether the minimum timer for diagnostics to run, VeTPSC_t_ETC_DiagMinEnbl, is LESS THAN calibration threshold, KeTPSC_t_ETC_DiagMinEnbl (set to an exemplary 225 ms), the minimum time after ignition on to allow main diagnostics to run before clearing; AND whether ReTPSC_b_Clear_ETC_Codes, indicating whether the low voltage fault clearing and fuel disable logic is active, is TRUE. If step  422  is TRUE, control continues in step  426 . If step  422  is false, control continues in step  428 . 
     In step  426 , control sets module diagnostics, including the ETC diagnostics to the Crank Transition state, by setting the following: VeTPSC_b_EngShutdownRqst, the low voltage fuel disable signal, is set to FALSE; VeTPSC_b_DisableFuel_MHC, the redundant fuel disable signal, is set to FALSE; VeTPSC_b_Clear_ETC_Codes, the signal enabling the clearing of all the ETC diagnostics and fail counters, is set to TRUE; and ReTPSC_b_Clear_ETC_Codes, the signal indicating that the low voltage fault clearing and fuel disable logic is active, is set to FALSEContinuing in step  426 , control executes the following functions: MngAPSR_CodeClear, which clears pedal sensor related faults; MngMCPR_DGCC — 12p5 ms, which clears processor communication faults; MngTPSR_DGCC — 12P5, which clears throttle body related faults; MngTPSR_MtrCntrl_CodeClear, which clears throttle sensor related faults; and MngVLTR_DGCC — 12P5, which clears reference voltage (5 Volt) related faultsLastly, VeTPSC_t_ETC_DiagMinEnbl is set equal to KeTPSC_t_ETC_DiagMinEnbl. After step  426  is completed control continues in step  430 , and ends. 
     In step  428 , control determines whether the main diagnostics timer, VeTPSC_t_ETC_DiagMinEnbl, is LESS THAN its calibrated threshold, KeTPSC_t_ETC_DiagMinEnbl, set to an exemplary 225 ms. If VeTPSC_t_ETC_DiagMinEnbl is GREATER THAN KeTPSC_t_ETC_DiagMinEnbl, indicating that enough time has passed since ignition ON to allow sufficient time for main diagnostics to run, then control continues in step  432 , if not control continues in step  434 . 
     In step  432 , control sets module diagnostics, including the ETC diagnostics, to the Crank Transition state, by setting the following: VeTPSC_b_EngShutdownRqst is set to FALSE; VeTPSC_b_DisableFuel_MHC is set to FALSE; VeTPSC_b_Clear_ETC_Codes is set to TRUE; and ReTPSC_b_Clear_ETC_Codes is set to FALSEContinuing in step  432 , control executes the following functions: MngAPSR_CodeClear, MngMCPR_DGCC — 12p5 ms, MngTPSR_DGCC — 12P5, MngTPSR_MtrCntrl_CodeClear, and MngVLTR_DGCC — 12P5. After step  432  is completed control continues in step  430 , and ends. 
     In step  434 , control sets the ETC diagnostics to normal by setting the following: VeTPSC_b_EngShutdownRqst is set to FALSE; VeTPSC_b_DisableFuel_MHC is set to FALSE; VeTPSC_b_Clear_ETC_Codes is set to FALSE; and ReTPSC_b_Clear_ETC_Codes is set to FALSE. After step  434  is completed control continues in step  430 , and ends. 
     Referring to  FIG. 4C , detailed steps for a periodic task loop are continued where the low voltage, non-cranking and low voltage recovery states are discussed in detailControl determines whether the vehicle is in the Low-voltage, Non-cranking state or the Low-voltage Recovery state in step  424 . In step  424  control determines whether the Run/Crank Ignition Controller input voltage, GetPMDR_U_RunCrank, is LESS THAN its calibrated threshold, KeTPSC_U_ECM_VoltMin, set to an exemplary 5.5 V, the low voltage check to disable the fuel and starter and to clear the ETC diagnostics; AND whether the powertrain voltage, GetPMDR_U_PT_Relay, is also LESS THAN KeTPSC_U_ECM_VoltMin; AND whether ReTPSD_b_EngPowerLimited, indicating whether engine power should be limited, is FALSE; AND whether ReTPSD_b_ReducedPwrActive_MCP, indicating whether the MCP has entered the limited-power mode, is FALSE; AND whether ReTPSC_b_Clear_ETC_Codes, indicating whether the low voltage fault clearing and fuel disable logic is active, is TRUE; AND whether the voltage hysteresis timer, VeTPSC_t_LowVoltageHysteresis, that measures the minimum time needed for voltage to become stable before the low voltage fault clearing request and fuel disable logic is cleared, is less than its calibrated threshold, KeTPSC_t_LowVoltageHysteresis, set to an exemplary 100 ms. If step  424  is true, then control sets the low voltage, non-cranking state in step  436 . If step  424  is false, then control sets the low-voltage recovery state and returns engine diagnostics, including ETC Diagnostics, for the ETC  18  and ETC diagnostic module  26  to normal in step  438 . 
     In step  436 , control enters the low voltage, non-cranking state by setting the following: VeTPSC_b_EngShutdownRqst is set to TRUE; VeTPSC_b_DisableFuel_MHC is set to TRUE; VeTPSC_b_Clear_ETC_Codes is set to TRUE; and ReTPSC_b_Clear_ETC_Codes is set to TRUEContinuing in step  436 , the fault clearing algorithm runs the following functions: MngAPSR_CodeClear, MngMCPR_DGCC — 12p5ms, MngTPSR_DGCC — 12P5, MngTPSR_MtrCntrl_CodeClear, and MngVLTR_DGCC — 12P5. Thus the fuel is disabled and all Diagnostic codes relating to the low-voltage condition are reset. After step  436  is completed, control continues to step  430  (see in  FIG. 4B ), and ends. 
     In step  438 , control enters the low voltage recovery state by setting the following: VeTPSC_b_EngShutdownRqst is set to FALSE, VeTPSC_b_DisableFuel_MHC is set to FALSE, VeTPSC_b_Clear_ETC_Codes is set to FALSE, and ReTPSC_b_Clear_ETC_Codes is set to FALSE. Thus the fuel is enabled and all module diagnostics are returned to normal. After step  438  is completed, control continues to step  430  (see in  FIG. 4B ), and ends.