Abstract: There is provided a method of specifying a location of occurrence of an abnormal sound, the method including: storing mapping data in a storage device, the mapping data prescribing mapping that receives, as inputs, a sound variable that matches a sound detected in a vehicle and a state variable of a drive-system device of the vehicle synchronized with the sound, and that outputs a location as a main cause of the sound; executing a sound signal acquisition process of acquiring a sound signal output from a microphone that detects a sound; a state variable acquisition process of acquiring the state variable of the drive-system device; and a specifying process of specifying the location of occurrence of the sound corresponding to the sound signal using the sound variable and the state variable as inputs to the mapping. There are also provided a non-transitory storage medium and an in-vehicle device.

Abstract: A torque converter clutch control system of a vehicle includes a target slip module and a slip control module. The target slip module determines a target torque converter clutch slip based on an average number of activated cylinders of an engine during a predetermined period. The slip control module controls a torque converter clutch based on the target torque converter clutch slip.

Abstract: Methods and systems are provided for performing a multiple gear downshift of a transmission gear by transiently operating in an intermediate gear. In response to ambient humidity and a condensate level in a charge air cooler, the transmission gear may be downshifted from a higher gear to an intermediate gear, and then to a requested lower gear. Downshifting through an intermediate gear may also be controlled based on the gear shift request.

Abstract: Methods and systems are provided for purging condensate from a charge air cooler to an engine intake. During an engine deceleration event, the vehicle is downshifted into a lower gear to increase RPM and airflow through a charge air cooler to purge stored condensate to the engine intake. By delivering condensate while an engine is not fueled, misfire events resulting from ingestion of water are reduced.

Abstract: A control device for a vehicle power transmitting apparatus is disclosed, having an electrically controlled differential portion operative to control an operating state of an electric motor to control a differential state, and a shifting portion forming part of a power transmitting path between the electrically controlled differential portion and drive wheels, which can minimize deterioration in power performance and degradation in controllability during the shifting. Shift interval altering means 70 is provided for altering an interval L from an operation initiation causing an automatic shifting portion 20 to execute a shifting, to an actual shift initiation depending on a kind of the shifting. This enables an appropriate interval L to be determined for the shifting, thereby obtaining adequate power performance while capable of avoiding a first electric motor M1 from operating in a region outside an operating range. Thus, degradation in controllability is minimized.

Abstract: There is provided a control system for a powertrain system including an electro-mechanical transmission operative in a plurality of fixed gear modes and continuously variable modes. The control system is adapted to identify preferred operating conditions for operating the powertrain in a fixed gear operating range state. The method comprises determining a range of permissible input torques. States for input torque are iteratively selected, and a motor torque output from the first electrical machine is optimized based upon the selected state for the input torque. A motor torque output from the second electrical machine is determined based upon the optimized motor torque output from the first electrical machine. A cost for each of the iteratively selected states for the input torque and the motor torques from the first and second electrical machines is calculated. A preferred operating range is identified based upon the plurality of costs.

Abstract: The present invention relates to a control device for a vehicular drive system which properly controls a shift in a transmission portion upon receipt of a shift demand to the transmission portion for precluding a given element of the differential portion 11 from high rotation. For a shift demand to an automatic transmission (20), the transmission portion shift limiting means (86) determines a permissible range in terms of a speed ratio of an automatic transmission (20) in consideration of a rotational speed of a given element of a differential portion (11) for thereby limiting a shifting of the automatic transmission portion (20) based on the permissible range. Thus, when the shift demand to the automatic transmission (20) is present, the given element of the differential portion (11) can be avoided from high rotation.

Abstract: A method for real time determination of a base torque value, representative of maximum available torque of an engine at a specified engine rpm, as a function of engine torque during predetermined engine conditions. The base torque value is used to determine shift points for an automatic transmission of an self propelled work machine.

Abstract: An ECU (Electronic Control Unit) executes a program including a step of detecting a driver's preference potential Hdr, a step of calculating a target engine output Ptgt using Hdr when a deceleration request is detected, a step of calculating a target slippage tsl using Hdr, a step of calculating a target engine speed tne, a step of calculating a target ISC (Idle Speed Control) opening tidle from Ptgt and tne, a step of assigning a guard value to tidle when tidle is smaller than the guard value, a step of calculating a current engine output Pnow and a step of calculating a motor output (regeneration quantity) Phv from (Ptgt-Pnow).

Abstract: A speed-limiting accessory drive system is provided that limits the speed range over which an engine-driven accessory operates while maintaining the operating speed range of the engine. A torque-transmitting mechanism is selectively engagable to operatively connect the engine and the accessory. A controller is configured to maintain the torque-transmitting mechanism in an engaged state only when monitored engine speed is within a predetermined speed range and to control a drive motor to drive the driven accessory when the monitored engine speed is not within the predetermined range. A method of controlling the speed of at least one driven accessory, which may be carried out using the speed-limiting accessory drive system, is also provided.

Abstract: A method and a device are provided for limiting the driving speed of a motor vehicle that allow a selectable, fixed fuel consumption per distance traveled to be maintained without limiting short-term acceleration. In this context, the driving speed is limited to a maximum value (vmaxbe), at which a predefined maximum fuel consumption (Besetpoint) for steady driving speed is not exceeded.

Abstract: An ECT-ECU includes an abrupt turbine speed increase learning control circuit which prevents simultaneous release of both a frictional engagement element to be released and a frictional engagement element to be engaged, a tie-up learning control circuit which prevents simultaneous engagement of both the frictional engagement element to be released and the frictional engagement element to be engaged, a determination circuit that determines whether one of tie-up learning control and abrupt turbine speed increase learning control is necessary based on the turbine speed, and a control circuit that prohibits execution of the tie-up learning control unless the number of trips after the abrupt turbine speed increase learning control has been executed is at least equal to a predetermined number, when it has been determined that the tie-up learning control is necessary.

Abstract: A control device for a vehicle controls a motor-driven pump at an appropriate timing when an internal combustion engine is stopped or starts. An ECU of the control device comprises an operation determination section which determines whether or not the motor-driven pump is operated depending on the value of an idling stop flag that makes the internal combustion engine stop, depending on a measured value output from an oil pressure sensor for measuring oil pressure in oil lines providing operation oil to a torque converter and a transmission, and depending on a measured value output from an oil temperature sensor for measuring the temperature of the operation oil; and a target electrical current calculation section for calculating a target value of electrical current to be supplied during the operation of the motor-driven oil pump depending on the determination result by the operation determination section.

Abstract: A vehicle, such as, e.g., a diesel-powered truck, has a transmission control system that, e.g., improves fuel efficiency and/or consumption. In some embodiments, the vehicle includes: an engine that powers said vehicle; a transmission to change ratios between engine speed and wheel speed; and at least one control unit configured to shift the transmission in a plurality of lower gears substantially against the governed speed of the engine and to shift the transmission in a plurality of higher gears substantially against the peak torque speed of the engine.

Abstract: The comfort level gear shift motor vehicle with an automated gear-shifting transmission is determined by shift parameters, which are dependent on driving parameters and on a shift program mode. The shift program mode identified through a characteristic parameter, which can vary a range of parameter values corresponding to a range of shift program modes. The method has the steps of detecting current values the driving parameters, detecting a current value of the characteristic parameter, determining respective minimum and maximum values that each of said shift parameters can assume within the range of characteristic parameter values as a function of the current driving parameter values, calculating actual shift parameter values as intermediate values between said maximum and minimum values for each of said shift parameters based on said current value of the characteristic parameter, and performing the gear shift with the actual shift parameter values.

Abstract: An automotive transmission shift controller to reduce a shift shock occurring while shifting from a reverse driving range to a forward driving range, and to improve durability at the same time. The controller detects a shift lever position, an engine revolution speed, a throttle valve opening, and a speed of the vehicle, and performing a shift control operation for shifting into a first gear if the shift lever is changed from a reverse driving range to a forward driving range and the engine revolution state is an idling state, and if the detected throttle valve opening and the vehicle speed respectively are not more than predetermined values.

Abstract: A system is described for minimizing engine torque disturbances that would otherwise cause degraded drive feel by a vehicle driver. The system utilizes multiple torque transmission paths of a transaxle unit mounted to the engine. The system manipulates the torque transmitted by adjusting the clutches of multiple torque transmission paths so that the torque disturbance in the engine results in relatively constant vehicle drive torque. In one example, a potential torque increase due to a change in engine air-fuel ratio is minimized by transmitted torque through multiple transmission paths.

Abstract: A vehicular lockup clutch-equipped transmission control apparatus is applied to a vehicle that includes a heater apparatus for heating a cabin by heat from an engine, a transmission that transfers power between the engine and a wheel, and a heat exchanger that conducts heat exchange between the engine and the transmission. The control apparatus controls a lockup clutch that is disposed between the engine and the transmission and that mechanically connects and disconnects a path of power, in accordance with a state of operation of the vehicle. The control apparatus includes a controller that determines whether a heating capability requested of the heater apparatus is at least a first predetermined level based on parameter related to a temperature inside the cabin. If it is determined that the heating capability requested of the heater apparatus is at least the first predetermined level, the controller restricts engagement of the lockup clutch.

Abstract: A direct injection type engine comprising a variable speed transmission. Engine control lines indicating the relationship between the engine rotational speed and required torque necessary for obtaining a required output are comprised of a first control line and a second control line at the high torque side and low speed side of the first control line. When the degree of activation of the exhaust gas purification device is low, the required torque and the engine rotational speed are made ones on the first control line in accordance with the required output, while when the degree of activation is high, the required torque and the engine rotational speed are made ones on the second control line in accordance with the required output.

Abstract: In order to consider a vehicle driving altitude in a shift control method, an atmospheric pressure is detected, values of shift control variables are reset based on the detected atmospheric pressure when a predetermined atmospheric pressure applying condition is satisfied, and shifting is controlled on the basis of the reset values of the shift control variables.

Abstract: A control system and calibration method are provided for a vehicle drive line having an automated master friction clutch. The control system utilizes engine torque data supplied by a serial communication data link to identify a clutch control parameter value corresponding to an urge-to-move position of the clutch. The clutch control parameter value identified by the calibration method is stored and utilized by the control system to control the engagement position of the automated clutch in an “urge to move” mode of operation. The inventive calibration method can be utilized across multiple vehicle platforms having different engine, clutch and transmission system components.

Abstract: A method and apparatus for operating an automatic transmission as a function of the engine rotational speed of a variable speed internal combustion engine. Upon a failure of the electronic control system, a return home of a motor vehicle under its own power is enabled. A delivery system delivers a working medium with which a transmission ratio adjusting device is actuated by a first control device that, in turn, is controlled by a pilot pressure that can be accurately changed by a second control device to actuate the transmission ratio adjusting device. The pilot pressure for controlling the first control device is changed by a third control device as a function of the rotational speed of the internal combustion engine when an adjusting device is switched out of a normal operation position into an emergency operation position.

Abstract: The present invention provides a drive control apparatus for driving an electric oil pump by supplying it with a predetermined operating voltage so as to decrease a load on the electric oil pump. The drive control apparatus detects a clutch hydraulic pressure supplied to the hydraulic control apparatus for the automatic transmission and drives the electric oil pump so that a required hydraulic pressure is maintained. In this case, the drive control apparatus detects an oil temperature of the hydraulic control apparatus for the automatic transmission, controls the operating voltage of the electric oil pump based on the oil temperature, and supplies the operating voltage to th electric oil pump. Accordingly, the hydraulic pressure supplied from the electric oil pump maintains the hydraulic pressure required for the hydraulic control of the automatic transmission and prevents supply of a greater hydraulic pressure than is required.

Abstract: A control apparatus of a vehicular automated manual transmission includes an input shaft provided with a plurality of drive gears, and an output shaft provided with a plurality of driven gears engaging with the drive gears, in which the drive gears and the driven gears form a plurality of transmission gear trains through engaging with each other. When down-shifting among the transmission gear trains, an engine speed Ne is set higher by a predetermined value &agr; than an input shaft rotational speed Nm. Thereby, the drag torque of the wet clutch works in such a manner that the input shaft rotational speed is increased, so that the difference of rotational speed between the input shaft and the output shaft becomes small. Accordingly, a transmission characteristic of the vehicular automated manual transmission with wet multi-disc type clutch can be improved.

Abstract: To connect a potentiometer (2) and a brush holder (1) of a servomotor of a throttle-valve actuator for a motor-vehicle engine with actuating electronics, use is made of a conductor bridge (3). This has supports (8, 9), by means of which it is supported in the throttle-valve actuator. The conductor bridge (3) is furthermore provided with two rigid conductor bars (4,5) for supplying energy to the servomotor and conductors for making contact with conductor tracks (21-24) of the potentiometer. The two conductor bars (4, 5) and the conductors are each connected to a plug pin (11-16) of a plug socket (10) of the conductor bridge (3).

Abstract: A system for controlling an automatic transmission of a vehicle which determines a downgrade or upgrade parameter based on the vehicle acceleration and selects one from among a plurality of shift maps (programs) based on the determined grade parameter to determine a gear ratio based on the selected shift program. The system includes a navigation system which stores the road information including the kinds of road. The system determines whether the vehicle runs on a relative road such an alley or a traffic jammed expressway based on the vehicle speed change, the vehicle-stopping-time and the navigation information and if it does, changes the upshift line of the level-road map in the direction in which the vehicle speed increases such that upshift is not likely to occur, or in the direction in which the vehicle speed decreases such that the upshift is more likely to occur, thereby enhancing driveability.

Abstract: The device for the control of an automatic transmission, especially a CVT, which is connected with an oscillatingly suspended drive mechanism, preferably an internal combustion engine for a motor vehicle with front-transverse drive mechanism, wherein the transmission has an electronic control, is provided with a sensor in the form of a piezoceramic transmitter on a torque support for the drive mechanism for producing high dynamic, to provide engine-torque equivalent signals which are fed to the electronic transmission control.

Abstract: In a method and apparatus for controlling a driving engine/transmission unit having a continuously variable automatic transmission, the transmission output torque acting upon the driving wheels of a vehicle and the engine reaction torque retroacting upon the driving engine can be adjusted by way of a regulated transmission variable.

Abstract: A device for the economical operation of motor vehicles having internal combustion engines and transmissions. For each gear speed of a transmission, it is possible to preset one of more threshold values, and when these values are exceeded a closed-loop control intervenes and prevents a further rise in the fuel consumption. By virtue of the fact that each gear speed is assigned at least one separate threshold, the driving behavior of the motor vehicle can be adapted to various traffic situations. If appropriate, it is possible to dispence even with setting a threshold for many gear speeds.

Abstract: For motor vehicles equipped with overdrive-equipped transmissions normally biased in one of the overdrive or non-overdrive modes of operation, a method for automatically biasing the transmission to the alternate mode of operation, and apparatus to practice the method. Normally used to bias transmissions from the overdrive to the non-overdrive mode of operation, the apparatus and method taught herein are particularly well-suited for operation in conjunction with automatic transmissions, and are actuated uniquely with each ignition run cycle. Alternatively, the method and apparatus may, with equal facility, incorporate other vehicle operations and conditions to actuate its overdrive biasing function.

Abstract: A control for confirming disengagement of a disengaging gear ratio (GR). Signals indicative of input shaft speed (ES or IS) are compared to signals indicative of output shaft rotational speed (OS) to determine if the quotient of input shaft rotational speed to output shaft rotational speed (IS/OS) remains outside an increasing-sized window (GR.+-.error, GR.+-.2*error, GR.+-.3*error).

Abstract: A shift position is controlled so that a vehicle driving force becomes larger than a corrected vehicle running resistance obtained by adding a correction value corresponding to a surplus driving force to an original running resistance. When the automatic speed control device is operative to drive the vehicle at a constant speed, the correction value is switched to a smaller value compared with when the same is inoperative so that the upshift easily occurs during the constant speed drive.

Abstract: Broadly, the present invention is directed to a method for controlling the shifting of a drag race vehicle with a controller for controlling an actuatable shifter assembly. This method includes resetting the controller followed by actuating the controller and launching the vehicle. At a predetermined engine speed value or after a first timed duration based on a predetermined engine speed value, the shifter assembly is actuated for a second timed duration to shift to a next higher gear. Finally, shifter assembly actuation is repeated until all of the gears of the vehicle desired to be shifted have been shifted. Another aspect of the present invention is a controller for controlling the shifting of a drag race vehicle shifter with an actuatable shifter assembly and which is activatable by a first duration timer or an rpm switch based on a predetermined engine speed value.

Abstract: A hydraulic control system for a hydraulically operated vehicle transmission. The system is configured to have a first gearshift mode for determining a gear ratio to be shifted to in accordance with a predetermined gearshift schedule based on detected parameters and a second gearshift mode for changing a gear ratio in accordance with at least one of an upshift command and a downshift command given by the driver. The first mode or the second mode is selected. And when the engine coolant temperature is found to be less than a predetermined value, the selection is prohibited or invalidated. This is because when the temperature is low, the viscosity of the ATF may be high and the time taken for completion of the gearshift is long, causing the driver to sense a time lag between the point at which the command was output and the point at which the actual gearshift is conducted.

Abstract: A shift control system of an automatic transmission controls operating forces on frictional engaging elements being engaged and disengaged with gear elements during a shift operation by generating a target transmission variable which prevents a rate of change of a corresponding target input rotational speed from inverting at the start of the shift operation and/or at the end of the shift operation. The target transmission variable may be the target input rotational speed, a target gear ratio, or other variable corresponding to a target input rotational speed which has a rate of change gradually changing at the start and end of the shift operation so as to avoid any inversion of the rate of change within a predetermined duration after the start of the shift operation and within a predetermined duration before the end of the shift operation.

Abstract: The present invention provides for a rapid down-shift to meet an insufficient drive force due to an increase in running resistance such as when ascending a slope. Speed change control is carried out by selecting a speed change step based on the vehicle speed and throttle opening. When there is no speed change requirement, the current running resistance is computed, and the maximum drive force for the current speed change step computed. The maximum drive force is computed based on the down-shift throttle opening corresponding to the current vehicle speed on a down-shift line from the current speed change step to a speed change step on a lower speed side. The running resistance and maximum drive force are compared, and when the maximum drive force is less than the running resistance a forceful down-shift is made.

Abstract: A preferred embodiment of the present invention includes a power take off ("PTO") controller used on a vehicle. The controller includes a PTO on/off switch, a brake/clutch ignore switch, and a PTO set/resume switch connected to an electronic controller. The controller sets the engine speed command to a PTO default speed in response to the PTO on/off switch being in an on position. By placing the brake/clutch ignore switch in an ignore position, the vehicle operator can use the brake or clutch without affecting the PTO engine speed.

Abstract: In an attempt to accomplish an object to absorb a driving torque difference caused by a difference in a change gear ratio between before and after shifting and to reduce a shift shock, adopted is such a constitution that target driving torque characteristics with which said driving torque before and after shifting will become nearly equal are stored, and engine torque control will be effected according to said characteristics. The control device is so constituted that, during shifting, the engine torque is decreased to suppress a driving torque variation resulting from inertia variation, and the engine torque before a specific period from the completion of shifting is outputted higher than the normal torque, and the engine torque before a specific period from the completion of shifting is outputted higher than the normal torque to reset to the normal engine torque after the specific period after the completion of shifting.

Abstract: A hydraulic control system for a power train including a shift speed mechanism, a frictional element for switching a shift characteristic of the shift speed mechanism, a hydraulic control mechanism for controlling a hydraulic pressure, a target shift time setting device for setting a target shift time based on an input speed difference of the shift speed mechanism through the shift operation and an input torque introduced to the shift speed mechanism, an angular acceleration calculator for calculating an angular acceleration of an input member of the shift speed mechanism based on the target shift time obtained through the target shift time setting device and the input speed change of the shift speed mechanism through the shift operation, an inertia hydraulic pressure setting device for setting an inertia hydraulic pressure for coping with a moment force due to a moment of inertia of a power transmitting system to the shift speed mechanism based on the angular acceleration of the input member of the shift spe

Abstract: In the present invention a solenoid is used on a ratchet shifter and is controlled through a relay by an electronic controller. This controller can be an analog, digital, or microprocessor driven device. The power supplied to the solenoid most conveniently is the existing battery of the vehicle. This power source is the only source needed, unlike pneumatic cylinders that require a bottle of compressed gas, e.g., air or CO.sub.2. The electronic controller is reset when the hold button is activated at the starting line. When the hold button is released, the vehicle launches violently at or above the rpm lock up of the transmission converter. This is sometimes referred to as "converter flash". If the rpm lock up of the converter is close to the rpm level setting for the first shift, or tire spin occurs, the rpm level will be reached prematurely causing the vehicle to shift early. The electronic controller has a preset time delay, disabling a shift, that begins when the hold button is released.

Abstract: A system and method for controlling gear ratio changes in an automatic transmission includes an electronic microprocessor, an electronic memory accessible to the microprocessor, solenoid-operated shift valves, pressure actuated friction clutches and brakes, a variable force solenoid-operated valve, a torque converter bypass friction clutch, and control algorithms that produce output signals to control the state of the solenoid-operated valves. The vehicle speed and engine speed at which upshifts and downshifts occur, according to a standard gear shift schedule, is compensated for loss of engine torque at conditions that differ from the conditions at which a reference shift schedule is defined. Vehicle speed is compensated for torque variation with reference to the ratio of current calculated engine torque divided by current engine output torque.

Abstract: A control method/system for controlling upshifting in an automated mechanical transmission system (10) provided with an engine compression brake (50) is provided. A control unit (54) is effective to operate the engine compression brake during a transmission upshift such that at initiation of an upshift the engine compression brake applies a minimum retarding torque to the engine, the retarding torque is then gradually increased to a maximum retarding torque value and, upon sensing that engine speed (ES) is within a predetermined value (REF.sub.1) of the synchronous value thereof, the retarding torque applied by the engine brake is caused to gradually decrease until such time as engine speed reaches the synchronous window therefor.

Abstract: A control for a motor vehicle transmission automatically shifts transmission gears as a function of at least a driving pedal position and vehicle speed on the basis of shifting performance graphs stored in memory, and takes a load state of the motor vehicle and the driving style of the driver into account. A fuzzy logic controller with a rule base evaluates various signals characterizing driving states of the motor vehicle, and thereupon generates the following control signals: a first correcting signal characterizing the load state of the motor vehicle, and a second correcting signal characterizing the driving style, bringing about a switchover to corresponding shifting performance graphs; and an inhibit signal preventing shifting events that would produce a dynamically unfavorable driving state.

Abstract: To improve shifting comfort in an automatic transmission, the transmission output shaft torque is kept as nearly constant as possible during the shifting operation by detecting, prior to and during the entire shift operation, the engine speed, the transmission input shaft speed and torque and the transmission output shaft torque or the torque of the drive wheels, and controlling the engagement and disengagement of transmission elements in accordance with those variables.

Abstract: In a speed change control method for setting the gearshift position of an automatic transmission for vehicles with a plurality of gearshift positions, to a position selected on the basis of vehicle speed and engine load, in accordance with a preset shift pattern for a first control mode, one of the gearshift positions is selected by fuzzy inference in accordance with at least one of parameter values which represent operating conditions of the vehicle, parameter values which represent driver's driving intention, and parameter values which represent road conditions. Further, the gearshift position of the automatic transmission is set to the position selected by the fuzzy inference only if the gearshift position selected by the fuzzy inference provides a lower speed than that provided by the gearshift position selected in accordance with the shift pattern for the first control mode.

Abstract: An apparatus automatically shifts a vehicle transmission, according to a shift pattern and on the basis of a detected parameter of the pattern. The shift pattern or the detected parameter is compensated by a compensating coefficient determined from an actual intake air quantity of the engine, and a required intake air quantity calculated from the throttle opening and the engine speed. The apparatus includes an arrangement for adjusting the compensating coefficient so as to prevent busy shifting actions of the transmission upon changing of the throttle opening, or an arrangement for determining the compensating coefficient so as to reflect the driver's desire for accelerating the vehicle, preferably depending upon the vehicle running condition.

Abstract: In a system for controlling a gear ratio of a multi-step geared or continuously variable automatic transmission of a vehicle based on determined parameter indicative of operating condition of the vehicle including a driving resistance, the driving resistance is calculated in an equation in which motive force-driving resistance=vehicle mass.times.acceleration using the law of motion. In the first embodiment, the calculation is carried out, without using a torque sensor, by applying an adjustment for torque consumption by a device such as an air conditioner and a torque loss caused by braking. In the second and third embodiments, the driving resistance is calculated using a torque sensor. Thus, with the arrangement, the driving resistance can be accurately determined applying appropriate adjustment, a gear ratio to be shifted is properly determined in any traveling condition including hill climbing.

Abstract: A hydraulic control system for an automatic transmission of an automotive vehicle with an exhaust braking unit is provided. This hydraulic control system serves to elevate hydraulic pressure utilized for actuating frictional elements of the automatic transmission during exhaust braking operation toward a preselected level when the pay load of the vehicle is greater than a preselected threshold value for securing tight engagement of the frictional elements without any slippage.

Abstract: In accordance with one aspect of the present invention, an apparatus is provided for a vehicle equipped with a drive system and a controller for regulating the operating speed of the drive system. The apparatus includes at least one sensor for sensing a vehicle parameter and producing a parameter signal in response to the sensed parameter. A diagnostic device is provided for receiving the parameter signal, processing the parameter signal to detect the presence of an undesirable operating condition; determining the severity of the undesirable operating condition in accordance with a preselected strategy and responsively producing a severity level signal. The controller receives the severity level signal and limits the maximum speed of the vehicle in response to the severity level signal, whereby the maximum allowable vehicle speed decreases as the severity level signal increases.