Equipment service vehicle having on-board diagnostic system

[0001] This application is a continuation of U.S. Ser. No. 09/500,506, filed Feb. 9, 2000, now U.S. Pat. No. 6,553,290, issued Feb. 22, 2003, hereby incorporated by reference.

[0002] This invention relates to diagnostic systems for equipment service vehicles. In particular, this invention relates to an on-board diagnostic system for equipment service vehicles.

[0003] Modern vehicles have become increasingly complex and difficult to maintain. In order to enable more efficient vehicle maintenance, it is desirable to be able to accurately diagnose malfunctioning subsystems, such as engine systems, transmission systems, and so on, as well as specific vehicle components. When a malfunction is not properly diagnosed, the result is typically that parts which are fully operational are repaired or replaced, that parts which are repairable are replaced, and/or that parts which are not fully operational are not repaired or replaced. Accurate diagnoses therefore allow more efficient vehicle maintenance by avoiding unnecessary repairs and replacements, and by enabling necessary repairs and replacements to be made.

[0004] It is known to provide electronic diagnostic systems to aid in the accurate diagnoses of vehicle malfunctions. Government Report No. CR-82-588-003, entitled STE/ICE-R Design Guide For Vehicle Diagnostic Connector Assemblies, February 1988, describes a diagnostic system used in connection with military vehicles. According to the approach described in this document, a military vehicle is provided with numerous sensors that are located throughout the vehicle and each of which obtains information pertaining to the health and operation of a subsystem of the vehicle. The sensors are used to measure typical parameters of interest such as engine RPM, engine temperature, fuel pressure, and so on. The sensors are connected by way of vehicle wiring to a common connector assembly. Diagnostic equipment provided at a maintenance depot is then capable of connecting to the various sensors by way of the connector assembly. At the maintenance depot, the diagnostic equipment can be utilized to perform tests on the vehicle to aid pinpointing the source of vehicle system malfunction.

[0005] In this arrangement, the sensors that are used by the diagnostic system are used exclusively by the diagnostic equipment at the maintenance depot, and not by other systems during normal operation of the vehicle. Additionally, in this arrangement, the connector assembly defines a hardwired analog interface between the sensors and the diagnostic equipment, and the diagnostic equipment expects signals appearing at given pins of the connector assembly to have predefined signal characteristics that are unique to the sensor utilized.

[0006] This approach suffers several disadvantages. First, this approach is expensive to implement because it requires numerous sensors above and beyond those required for normal operation of the vehicle. Additionally, the required sensors typically have unique signal characteristics that are specifically matched to the diagnostic equipment, and therefore the sensors are specialty items that are more expensive and not commonly available.

[0007] Second, this approach results in a diagnostic system with an unduly limited capability to accurately diagnose system faults. The capabilities of the diagnostic system are limited by the fact that the diagnostic system only utilizes information that is available from the diagnostic system sensors and not from other sources of information available on-board the vehicle. Therefore, the number of different types of information that can be obtained is limited to the number of diagnostic system sensors utilized. Further, because the sensors that are utilized tend to be specialty items as previously noted, they often do not incorporate the latest advances in sensor technology that provide performance/durability improvements over earlier sensor technologies. This further limits the accuracy of the diagnostic system as compared to that which could otherwise be achieved.

[0008] Finally, this approach is unduly cumbersome to utilize. As previously noted, the diagnostic equipment is provided at a maintenance depot and not on-board the vehicle. Therefore, in order to have a vehicle malfunction diagnosed, the vehicle must be brought to the maintenance depot. This requirement is inconvenient and limits the potential for field servicing of vehicles to minimize the amount of time that the vehicle is out of service for maintenance reasons.

[0009] The present invention overcomes the problems of conventional diagnostic systems for equipment service vehicles. In particular, in one particularly preferred embodiment, the invention provides an equipment service vehicle comprising a network communication link, a plurality of vehicle subsystems, a test control module, and an operator interface. The vehicle subsystems each comprise a mechanical system and an electronic control system that controls the mechanical system. For example, one vehicle subsystem may comprise an engine and an engine control system, and another vehicle subsystem may comprise a transmission and a transmission control system. Each respective electronic control system is connected to the network communication link and transmits information pertaining to the health and operation of the associated mechanical system on the network communication link. The test control module is coupled to the plurality of vehicle subsystems by way of the network communication link. The test control module is programmed to acquire at least some of the information pertaining to the health and operation of the mechanical system. The operator interface is coupled to the test control module and comprises a display that displays the at least some information pertaining to the health and operation of the mechanical system.

[0010] According to another particularly preferred embodiment of the invention, the invention provides a method of diagnosing a fault on an equipment service vehicle comprising providing the equipment service vehicle with an on-board diagnostic system. The on board diagnostic system comprises a test control module and an operator interface that are mounted on the vehicle. The method also comprises displaying a menu of test options to an operator using the operator interface and receiving an operator input using the operator interface. The input is indicative of a menu selection made by the operator, and the menu selection indicates a test selected by the operator to be performed on the vehicle. Further, the method comprises performing the selected test on the vehicle in response to the operator input, and displaying results of the test to the operator using the operator interface.

[0011] According to yet another particularly preferred embodiment of the invention, the invention provides an equipment service vehicle comprising a network communication link, an engine system, a transmission system, and an operator interface. The engine system includes an engine and an electronic engine control system that is coupled to the engine and to the network communication link. The electronic engine control system controls the engine and transmits information pertaining to the health and operation of the engine on the network communication link. The transmission system includes a transmission and an electronic transmission control system. The electronic transmission control system controls the transmission and transmits information pertaining to the health and operation of the transmission on the network communication link. The operator interface is coupled to the network communication link and includes a display that displays the health and operation information of the engine and the transmission to a human operator.

[0012] Other objects, features, and advantages of the present invention will become apparent to those skilled in the art from the following detailed description and accompanying drawings. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not limitation. Many modifications and changes within the scope of the present invention may be made without departing from the spirit thereof, and the invention includes all such modifications.

[0013] FIG. 1 is a schematic view of a military vehicle having a diagnostic system according to one embodiment of the present invention;

[0014] FIG. 2 is a block diagram of the diagnostic system of FIG. 1 showing selected aspects of the diagnostic system in greater detail;

[0015] FIG. 3 is a menu displayed by a display of the diagnostic system of FIG. 1 showing various services offered by the diagnostic system;

[0016] FIG. 4 is a flow chart showing the operation of the diagnostic system of FIG. 1 to perform a diagnostic test procedure;

[0017] FIG. 5 is a schematic view of a firefighting vehicle having a diagnostic system in accordance with FIGS. 1-4;

[0018] FIG. 6 is a schematic view of a mixing vehicle having a diagnostic system in accordance with FIGS. 1-4;

[0019] FIG. 7 is a schematic view of a refuse handling vehicle having a diagnostic system in accordance with FIGS. 1-4; and

[0020] FIG. 8 is a schematic view of a snow removal vehicle having a diagnostic system in accordance with FIGS. 1-4.

[0021] Referring now to FIG. 1, a preferred embodiment of an equipment service vehicle 10 having a diagnostic system 12 according to an embodiment of the invention is illustrated. By way of overview, the diagnostic system 12 comprises an intelligent display module 14, a test interface module 21 connected to a plurality of sensors 22, and a plurality of additional vehicle control systems 24-30. The intelligent display module 14, the test interface module 21, and the plurality of additional vehicle control systems 24-30 are interconnected with each other by way of a network communication link 32.

[0022] More specifically, the vehicle 10 is a military vehicle and, in particular, a medium tactical vehicle. However, it should be understood that the diagnostic system 12 of FIG. 1 could also be used with other types of military vehicles. For example, the diagnostic system 12 could be used in connection with heavy equipment transporter vehicles, which are used to transport battle tanks, fighting and recovery vehicles, self-propelled howitzers, construction equipment and other types of equipment. These types of vehicles are useable on primary, secondary, and unimproved roads and trails, and are able to transport in excess of 100,000 pounds or even in the range of 200,000 pounds or more. The diagnostic system 12 can also be used in connection with palletized load transport vehicles, in which a mobile truck and trailer form a self-contained system capable of loading and unloading a wide range of cargo without the need for forklifts or other material handling equipment. Such trucks are provided with a demountable cargo bed and a hydraulically powered arm with a hook that lifts the cargo bed on or off the truck. These trucks may be also provided with a crane to drop off the pallets individually if the entire load is not needed. Further, the diagnostic system 12 can also be used in connection with trucks designed for carrying payloads for cross country military missions. Such trucks may include, for example, cargo trucks, tractors, fuel servicing trucks, portable water trucks, and recovery vehicles (with crane and winch). Such trucks are capable of passing through water crossings three or four or more feet deep. These trucks can also be used for missile transports/launchers, resupply of fueled artillery ammunition and forward area rearm vehicles, refueling of tracked and wheeled vehicles and helicopters, and recovery of disabled wheeled and tracked vehicles. The diagnostic system 12 can be used in connection with a wide range of other military vehicles as well.

[0023] The intelligent display module 14 provides an operator interface to the diagnostic system 12 and also provides intelligence used to conduct diagnostic tests and other services. In particular, the intelligent display module 14 includes a test control module 15 (which further includes a microprocessor 16 and a diagnostic program 17) and an operator interface 18 (which further includes a display 19 and a keypad 20) (see FIG. 2).

[0024] In the preferred embodiment, the test control module 15 and the operator interface 18 are provided as a single, integrated unit (namely, the intelligent display module 14) and share the same housing as well as at least some of the internal electronics. Other arrangements are possible, however. For example, as can be easily imagined, it would also be possible to provide the test control module 15 and the operator interface 18 in the form of separate physical units, although this arrangement is not preferred for reasons of increased cost and parts count. Both the test control module 15 and the operator interface 18 can be obtained in the form of a single, integrated unit from Advanced Technology, Inc., Elkhart, Ind. 46517. This product provides a generic flat panel 4 line20 character display 19, four button keypad 20, microprocessor 16, and memory that is capable of being programmed with a program (such as the diagnostic program 17) to customize the intelligent display module for a particular application. Of course, a more (or less) elaborate intelligent display module could also be utilized.

[0025] Also in the preferred embodiment, the intelligent display module 14 is semi-permanently mounted within the vehicle 10. By semi-permanently mounted, it is meant that the intelligent display module 14 is mounted within the vehicle 10 in a manner that is sufficiently rugged to withstand normal operation of the vehicle for extended periods of time (at least days or weeks) and still remain operational. However, that is not to say that the intelligent display module 14 is mounted such that it can never be removed (e.g., for servicing of the intelligent display module) without significantly degrading the structural integrity of the mounting structure employed to mount the intelligent display module 14 to the remainder of the vehicle 10. The intelligent display module 14 is preferably mounted in an operator compartment of the vehicle 10, for example, in a storage compartment within the operator compartment or on an operator panel provided on the dashboard.

[0026] The operation of the test control module 15, and in particular of the microprocessor 16 to execute the diagnostic program 17, is shown and described in greater detail below in conjunction with the flow chart of FIG. 4. In general, the microprocessor 16 executes the diagnostic program 17 to diagnose subsystem faults, to display fault information, to maintain vehicle maintenance records, and to perform data logging for system diagnosis and/or for accident reconstruction. Depending on the application, it may be desirable to incorporate additional services as well, or to incorporate fewer than all of these services.

[0027] The operator interface 18 includes the display 19 which is used to communicate (and, in particular, to display) information to the operator. For example, the display 19 is used to prompt the operator to enter information into the keypad 20, or to take certain actions with respect to the vehicle during testing (e.g., bring the engine to a specified RPM level). The display 19 is also used to display a menu or series of menus to allow the operator to select a test to be performed or to select another service of the intelligent display module 14 to be utilized. The display 19 is also used to display status information during system startup and during testing, and to display any error messages that arise during system startup or during testing. The display 19 is also used to display input data and fault mode indicators from control systems 24-30, and any other information from additional vehicle subsystems. The display 19 is also used to display information from discrete sensors such as the sensors 22. The display 19 is also used to display the results of diagnostic tests that are performed (e.g., a pass/fail message or other message).

[0028] Preferably, the display 19 displays all of this information to the operator in a user-friendly format as opposed to in the form of codes that must be interpreted by reference to a separate test or service manual. This is achieved in straightforward fashion by storing in the memory of the intelligent display module 14 information of the type commonly published in such manuals to facilitate manual interpretation of such codes, and using this information to perform the translation automatically. Likewise, as previously noted, the display 19 is used to prompt the operator to take certain actions with respect to the vehicle during testing and to otherwise step the operator through any test procedures, without reference to a test manual. This allows the amount of operator training to be reduced.

[0029] The operator interface 18 also includes the keypad 20 which is used to accept or receive operator inputs. For example, the keypad 20 is used to allow the user to scroll through and otherwise navigate menus displayed by the display 19 (e.g., menus of possible tests to be performed on the vehicle 20), and to select menu items from those menus.

[0030] As previously noted, it would also be possible to utilize a more elaborate intelligent display module. For example, a more elaborate keypad 20 could be utilized if more data entry capability is desired. In this regard, however, it is noted that the intelligent display module 14 also preferably includes a communication port that allows the display module to communicate with a personal computer 33 by way of a communication link 36 (see FIG. 2). The personal computer 33 can be used to retrieve, manipulate and examine data stored within the intelligent display module 14. For example, if the intelligent display module 14 includes a data logger as described below, the personal computer can be used to retrieve and examine the information stored by the data logger. Likewise, if the intelligent display module 14 implements a vehicle maintenance jacket, the personal computer 33 can be used to retrieve and modify data stored in the vehicle maintenance jacket. Further, using the personal computer 33, it is possible to integrate the diagnostic system 12 with an interactive electronic technical manual (IETM), to allow the interactive electronic technical manual to access the data available from the diagnostic system 12.

[0031] The test interface module 21 accepts requests from the intelligent display module 14 for information from the sensors 22, retrieves the requested information from the respective sensor 22, converts input signals from the respective sensor 22 into a format that is compatible with the network communication link 32, and transmits the information from the respective sensor 22 to the intelligent display module 14 via the network communication link 32. The test interface module 21 is therefore preferably implemented as a passive unit with no standard broadcasts that burden the communication link 32. As a result, in operation, the test interface module 21 does not regularly transmit data on the network communication link 32. Rather, the test interface module 21 passively monitors the network communication link 32 for information requests directed to the interface module 21. When an information request is received, the test interface module 21 obtains the requested information from the relevant sensor 22, and then transmits the requested information on the network communication link 32 to the intelligent display module 14.

[0032] The test interface module 21 may, for example, include as many inputs as there are sensors 22. Each input may include associated switches for configuring the input, an analog-to-digital converter to convert analog signals to a digital format, and any other signal processing circuitry. The number of inputs is not important, since it is possible to use fewer test interface modules each with a larger number of inputs, or more test interface modules each with a smaller number of inputs. The number of inputs is not limited in any particular way and is determined by need.

[0033] In practice, the test interface module 21 may be a commercially available unit capable of putting information from discrete sensors onto a network communication link such as SAE (Society of Automotive Engineers) J1708. The test interface module 21 preferably also meets applicable standards for underhood installation, such as SAE J1455, to allow the test interface module to be located in close proximity to the sensors 22 to reduce wiring. The test interface module may, for example, be obtained from Advanced Technology Inc., Elkhart, Ind. 46517 (PN 3246282). Again, however, a wide range of devices of varying construction and complexity could be utilized to implement the test interface module 21.

[0034] The test interface module 21 is connected to the plurality of sensors 22 which are each capable of obtaining information pertaining to the health and operation of a vehicle subsystem. Health and operation are interrelated and information that pertains to one will, at least to some extent, pertain to the other as well. The sensors 22 are discrete sensors in the sense that they are not integrally provided with the control systems 24-30 and associated controlled mechanical systems (e.g., engine, transmission, and so on) 34-40. The sensors are add-on devices that are used only in connection with the intelligent display module 14. In general, discrete sensors are preferably only used when the information provided by the sensor is not otherwise available on the network communication link 32. In FIG. 2, the sensors 22 are shown to include a fuel filter inlet pressure sensor 22a, fuel pump outlet pressure sensor 22b, fuel return pressure sensor 22c, oil filter sensors 22d, an air cleaner pressure sensor 22e, a fuel differential pressure switch 22f, and a shunt resistor 22g (used to determine compression imbalance based on unequal current peaks in the starter current).

[0035] In addition to the intelligent display module 14 and the test interface module 21, the diagnostic system 12 also includes a plurality of additional vehicle control systems 24-30, as previously noted. As shown in FIG. 2, the control system 24 is a central tire inflation control system that controls a central tire inflation system (CTIS) 34, the control system 26 is an anti-lock brake control system that controls an anti-lock brake system (ABS) 36, the control system 28 is a transmission control system that controls a transmission 38, and the control system 30 is an engine control system that controls an engine 40. The vehicle subsystems formed by the mechanical systems 34-40 and associated control systems 24-30 are conventional and are chosen in accordance with the intended use of the vehicle 10.

[0036] The control systems 24-30 each store information pertaining to the health and operation of a respective controlled system. The control systems 24-30 are capable of being queried and, in response, making the requested information available on the network communication link 32. Because the vast amount of information required for performing most diagnostic tests of interest is available from the control systems 24-30 by way of the network communication link 32, it is possible to drastically reduce the number of discrete sensors 22 that are required. Thus, as just noted, discrete sensors are preferably only used when the information provided by the sensor is not otherwise available on the network communication link 32.

[0037] Typically, each of the control systems 24-30 comprises a microprocessor-based electronic control unit (ECU) that is connected to the network communication link 32. When the intelligent display module 14 requires status information pertaining to one of the mechanical systems 34-40, the intelligent display module 14 issues a request for the information to the respective one of the control systems 24-30. The respective control system then responds by making the requested information available on the network communication link 32.

[0038] Typical ECUs for transmission and engine control systems are capable of producing fault codes and transmitting the fault codes on the network communication link 32. Depending on the type of fault, the fault codes may be transmitted automatically or alternative only in response to a specific request for fault information. Typical ECUs for central tire inflation systems and anti-lock brake systems also transmit fault codes but, in most commercially available systems, fault codes are transmitted only in response to specific requests for fault information. When a fault code is transmitted on the network communication link 32, the intelligent display module 14 receives the fault codes from the network communication link 32, interprets the fault codes, and displays the interpreted fault codes to a human operator using the display 19.

[0039] Referring now to FIG. 3, in general, during operation, the display 19 displays menus to the operator and the keypad receives operator inputs used to navigate the menu, make menu selections, and begin testing. Assuming other services are also provided, the operator is first prompted to select an option from among a list of options that includes options of other services provided by the intelligent display module 14. The list of options may include, for example, an option 50 to perform vehicle diagnostic testing, an option 52 to view engine codes, an option 54 to view transmission codes, an option 56 to view ABS codes, an option 58 to view CTIS codes, an 60 option to view and/or modify data in the vehicle maintenance jacket, and an option 62 to view information stored in a data logger. Given that the display 19 is a four line display in the preferred embodiment, a vertically sliding winding 64 is used to scroll through the options, and the user presses a select button on the keypad 20 when a cursor 66 is positioned on the desired option. As previously noted, other options may also be provided.

[0040] Referring now to FIG. 4, a flow chart showing the operation of the diagnostic system of FIGS. 1-2 to perform a diagnostic test is illustrated. In connection with military vehicles, the diagnostic system 12 may for example be made capable of performing the following diagnostic tests, all of which provide information pertaining to the health and operation of the tested subsystem:

[0041] 0041

	Test	Exemplary
	Description and	Measurement
Test	Application	Range(s)
ENGINE TESTS
Engine RPM (AVE)	Measures average speed of	50-5000 RPM
	engine crankshaft.
Engine RPM,	Measures cranking RPM.	50-1500 RPM
Cranking SI only	Performed with ignition ON.
	Inhibit spark plug firing
	allowing cranking without
	starting.
Power Test	Measures engine's power	500-3500 RPM/s
(RPM/SEC)	producing potential in units
	of RPM/SEC. Used when
	programmed engine
	constants and
	corresponding Vehicle
	Identification Number (VID)
	have not been established.
Power Test (%	Measures percentage of	0-100%
Power)	engine's power producing
	potential compared to full
	power of a new engine.
Compression	Evaluates relative cylinder	0-90%
Unbalance (%)	compression and displays
	percent difference between
	the highest and the lowest
	compression values in an
	engine cycle.
IGNITION TESTS
Dwell Angle (TDC)	Measures number of	10-72
	degrees that the points are	2000 RPM
	closed.
Points Voltage	Measures voltage drop	0-2 VDC
(VDC)	across the points (points
	positive to battery return).
Coil Primary	Measures voltage available	0-32 VDC
	at the coil positive terminal
	of the operating condition of
	the coil.
FUEL/AIR SYSTEM TESTS
Fuel Supply Pressure		0-100 psi
(psi)
Fuel Supply Pressure	This test measures the	0-10 psi
(psi)	outlet pressure of the fuel	0-30 psi
	pump.	0-100 psi
		0-300 psi
Fuel Return Pressure	Measures return pressure to	0-100 psi
(psi)	detect return line blockage,
	leaks, or insufficient
	restrictor back pressure.
Fuel Filter Pressure	Detects clogging via	PASS/FAIL
Drop (PASS/FAIL)	opening of a differential
	pressure switch across the
	secondary fuel filter.
Fuel Solenoid	Measures the voltage	0-32 VDC
Voltage (VDC)	present at the fuel shutoff
	solenoid positive terminal.
Air Cleaner Pressure	Measures suction vacuum in	0-60 in. H2O
Drop (RIGHT) (In	air intake after the air
H2O)	cleaner relative to ambient
	air pressure to detect extent
	of air cleaner clogging.
Air Cleaner Pressure	Second air cleaner on dual	0-60 in. H2O
Drop (LEFT) (In H2O)	intake systems.
Turbocharger Outlet	Measures discharge	0-50 in. Hg
Pressure (RIGHT) (In	pressure of the
Hg)	turbocharger.
Turbocharger Outlet	Second turbocharger on	0-50 in. Hg
Pressure (LEFT) (In	dual intake systems.
Hg)
Airbox Pressure	Measures the airbox	0-20 in. Hg
(In Hg)	pressure of two stroke	0-50 in. Hg
	engines. This measurement
	is useful in detecting air
	induction path obstructions
	or leaks.
Intake Manifold	Spark ignition engine intake	0-30 in. Hg
Vacuum (In Hg)	system evaluation.
Intake Manifold	Spark ignition engine intake	0-30 in. Hg
Vacuum Variation	system evaluation.
(In Hg)
LUBRICATION/COOLING
SYSTEM TESTS
Engine Oil Pressure	Measures engine oil	0-100 psi
(psi)	pressure.
Engine Oil Filter	Measures the pressure drop	0-25 psi
	across the engine oil filter
	as indicator of filter element
	clogging.
Engine Oil	Primarily applicable to air	120-300 F.
Temperature ( F.)	cooled engines. Requires
	transducer output shorting
	switch on vehicle to
	perform system zero offset
	test.
Engine Coolant	Transducer output shorting	120-300 F.
Temperature ( F.)	switch on vehicle required.
STARTING/CHARGING
SYSTEM TESTS
Battery Voltage	Measure battery voltage at	0-32 VDC
(VDC)	or near battery terminals.
Starter Motor	Measures the voltage	0-32 VDC
Voltage (VDC)	present at the starter motor
	positive terminal.
Starter Negative	Measures voltage drop on	0-2 VDC
Cable Voltage Drop	starter path. A high voltage
(VDC)	indicates excessive ground
	path resistance.
Starter Solenoid	Measures voltage present at	0-32 VDC
Volts (VDC)	the starter solenoid's
	positive terminal. Measures
	current through battery
	ground path shunt.
Starter Current,	Measures starter current.	0-1000 A
Average (amps)		0-2000 A
Starter Current First	Provides a good overall	0-1000 A
Peak (Peak Amps,	assessment of complete	0-2000 A
DC)	starting system. Tests
	condition of the starting
	circuit and battery's ability
	to deliver starting current.
	The measurement is made
	at the moment the starter is
	engaged and prior to
	armature movement. Peak
	currents less than nominal
	indicate relatively high
	resistance caused by poor
	connections, faulty wiring,
	or low battery voltage.
Battery Internal	Evaluate battery condition	0-999.9 mohm
Resistance	by measuring battery
(Milliohms)	voltage and current
	simultaneously.
Starter Circuit	Measures the combined	0-999.9 mohm
Resistance	resistance of the starter
(Milliohms)	circuit internal to the
	batteries.
Battery Resistance	Measures rate of change of	0-999.9 mohm/s
Change	battery resistance as an
(Milliohms/sec)	indicator of battery
	condition.
Battery Current	Measures current to or from	999-1000 A
	the battery.	999-2000 A
Battery Electrolyte	Determines whether	PASS/FAIL
Level (PASS/FAIL)	electrolyte in the sensed cell
	is of sufficient level (i.e., in
	contact with electrolyte
	probe).
Alternator/Generator	Measures output voltage of	0-32 VDC
Output Voltage	generator/alternator.
(VDC)
Alternator/	Measures voltage present at	0-32 VDC
Generator Field	alternator/generator field
Voltage (VDC)	windings.
Alternator/	Measures voltage drop in	0-2 VDC
Generator Negative	ground cable and
Cable Voltage Drop	connection between
(VDC)	alternator/generator ground
	terminal and battery
	negative terminal.
Alternator Output	Measures voltage output at	0-3 VAC
Current Sense	the current transformer in
(VAC-RMS)	650 ampere alternator.
Alternator AC	Measures alternator output	0-22 VAC
Voltage Sense	voltage.
(VAC-RMS)

[0042] In general, the specific diagnostic tests that are performed will be selected depending on the application, including the type of equipment utilized by the vehicle 10. Most or all tests may be simple in nature from a data acquisition standpoint, involving primarily bringing the vehicle to a particular operating condition (e.g., engine speed), if necessary, and obtaining information from a suitable transducer constructed and placed to measure the parameter of interest, although more elaborate tests could also be utilized. Any number of different vehicle parameters can be measured, each providing a separate data point regarding the operational health of the vehicle. By providing an operator with enough data points regarding the operational health of the vehicle, the operator can use this information in a known way to determine whether the vehicle is in good working order, or whether some subsystem or component thereof needs to be repaired or replaced.

[0043] At step 102, once the vehicle diagnostic option is selected, the display 19 displays a menu of various tests that are available to the operator, and the operator is prompted to select a test from the test menu. Again, the list of options may comprise dozens of options, such as some or all of those listed above, and/or tests other than those listed above, and the operator can scroll through the menu and selected the desired option.

[0044] At Step 104, the operator is prompted to perform a vehicle related action. This step, which may or may not be necessary depending on the type of test performed, may be used to prompt the operator to start the engine to develop fuel pressure, oil pressure, and so on, depending on which vehicle parameter is tested. For example, if it is desired to test the operational health of the battery, then the operator may be prompted to engage the starter for a predetermined amount of time to establish a current draw on the battery.

[0045] At Step 106, the intelligent display module 14 issues a request for information from the test interface module 21and/or from one or more of the control systems 24-30. As previously noted, the test interface module 21 does not continually broadcast information on the network communication link 32, because the sensors 22 connected to the test interface module are used only for diagnostic testing and because presumably diagnostic testing will be performed only infrequently. Therefore, when the intelligent display module 14 needs information from one of the sensors 22 pursuant to a test requested to be performed by the operator at the operator interface 18, the intelligent display module 14 requests the test interface module 21 for this information.

[0046] Alternatively, the needed information may be of a type that is available from one of the control systems 24-30. The control systems 24-30 are not only able to acquire information from sensors located within the systems 34-40, but are also able to maintain information derived from sensors located within the systems 34-40. For example, the engine control system 30 may maintain information pertaining to the average RPM of the engine, which is a parameter that is not directly measurable but that can be easily calculated based on parameters that are directly measurable. Through the network communication link 32, all of this information is made available to the diagnostic system 12. When the intelligent display module 14 needs information from one of the control systems 24-30 pursuant to a test requested to be performed by the operator at the operator interface 18, the intelligent display module 14 requests the respective control system for this information.

[0047] At Step 108, the requested information is retrieved from one of the sensors 22 by the test interface module 21, or from memory or an internal sensor by the respective control system 24-30. At step 110, the information is transmitted from the test interface module 21 or from one of the control systems 24-30 to the intelligent display module 14 by way of the network communication link 32.

[0048] At step 112, the input status information is processed at the intelligent display module 14. For example, if fuel supply pressure is measured by one of the sensors 22, then the measured fuel supply pressure may be compared with upper and lower benchmark values to determine whether the fuel pressure is at an acceptable level, or whether it is too high or too low. Finally, at step 114, the results of the test are displayed to the operator.

[0049] As has been previously noted, in addition to performing diagnostic tests, the intelligent display module 14 can also be used to provide other services to an operator. For example, the intelligent display module 14 can be used to allow the operator to view engine codes, to view transmission codes, to view ABS codes, and to view CTIS codes. In practice, these services can be implemented simply by allowing acquiring the respective codes from the respective control system 24-30, and displaying the codes to the operator. Additionally, the control systems 24-30 may automatically transmit fault information on the network communication link 32, and the intelligent display module 14 can listen for such fault information and display the fault information to the user when it appears on the network communication link 32.

[0050] The intelligent display module 14 also includes sufficient memory to allow maintenance information to be stored therein to implement maintenance jacket functionality. The maintenance log may consist of a table comprising a variety of fields, such as registration numbers, chassis serial number, vehicle codes, and dates and descriptions of maintenance actions performed. This information may be retrieved and manipulated utilizing the computer 34 when the vehicle 10 is taken to a maintenance depot. If the computer 34 is provided with an interactive electronic technical manual (IETM) for the vehicle 10, this allows the IETM to have access to all of the diagnostic data acquired by the intelligent display module 14 as well as all of the maintenance data stored by the intelligent display module 14. This greatly enhances the ability to perform vehicle maintenance and diagnostics on the vehicle 10.

[0051] Additionally, sufficient memory capacity is preferably provided so that status information from the test interface module 21 as well as the control systems 24-30 can be sampled and stored at frequent, regular intervals in a circular data queue (i.e., with new data eventually replacing old data in the circular queue). This allows the intelligent display module 14 to provide a data logger service so that input data acquired over a period of time can be viewed to allow an assessment of dynamic conditions leading to a fault to be evaluated. Additionally, the vehicle is preferably provided with one more sensors that indicate whether a severe malfunction (e.g., the vehicle being involved in an accident) has occurred. When inputs from these sensors indicates that a severe malfunction has occurred, data logging is stopped, so that data leading up to the severe malfunction is stored in a manner similar to a so-called black box recorder.

[0052] Referring now to FIG. 5, a schematic view of another type of equipment service vehicle 110 that utilizes the diagnostic system 12 of FIGS. 1-4 is shown. The equipment service vehicle 110 is a firefighting vehicle and comprises a water dispensing system 115 including water hoses, pumps, control valves, and so on, used to direct water at the scene of a fire. The firefighting vehicle 110 may also comprise a foam dispensing system 118 as an alternative fire extinguishing system. The firefighting vehicle 110 also comprises emergency lighting 124, which may in practice be red and white or red, white and blue flashing lights, as well as an emergency horn 126 and an emergency siren 128 used, among other things, for alerting motorists to the presence of the firefighting vehicle 110 in transit to or at the scene of a fire. The firefighting vehicle 110 may also comprise an extendable aerial 131 that supports a basket 132 used to vertically carry firefighting personnel to an emergency situation at the scene of a fire. The diagnostic system 12 may be used to diagnose vehicle malfunctions in the manner described above in connection with the vehicle 10, as well as to diagnose malfunctions of the specialized systems described above found on firefighting vehicles.

[0053] Referring now to FIG. 6, a schematic view of another type of equipment service vehicle 210 that utilizes the diagnostic system 12 of FIGS. 1-4 is shown. The equipment service vehicle 210 is a mixing vehicle such as a cement mixing vehicle. The mixing vehicle 210 comprises a rotatable mixing drum 215 that is driven by engine power from the engine 40 via a power takeoff mechanism 220. Rotation of the mixing drum 215 is controlled under operator control using a control system 225. The mixing vehicle 210 also includes a dispenser 230 that dispenses the mixed matter or material, for example, mixed cement. The diagnostic system 12 may be used to diagnose vehicle malfunctions in the manner described above in connection with the vehicle 10, as well as to diagnose malfunctions of the specialized systems described above found on mixing vehicles.

[0054] Referring now to FIG. 7, a schematic view of another type of equipment service vehicle 310 that utilizes the diagnostic system 12 of FIGS. 1-4 is shown. The equipment service vehicle 310 is a refuse handling vehicle and comprises one or more refuse compartments 315 for storing collected refuse and other materials such as goods for recycling. The refuse handling vehicle 310 also includes a hydraulic compactor 317 for compacting collected refuse. The hydraulic compactor 317 is driven by engine power from the engine 40 via a power takeoff mechanism 320. The refuse handling vehicle may also include an automatic loading or tipping system 325 for loading large refuse containers and for transferring the contents of the refuse containers into one of the compartments 315. The loading system 325 as well as the hydraulic compactor may controlled under operator control using a control system 330. The diagnostic system 12 may be used to diagnose vehicle malfunctions in the manner described above in connection with the vehicle 10, as well as to diagnose malfunctions of the specialized systems described above found on refuse handling vehicles.

[0055] Referring now to FIG. 8, a schematic view of another type of equipment service vehicle 410 that utilizes the diagnostic system 12 of FIGS. 1-4 is shown. The equipment service vehicle 410 is a snow removal vehicle and comprises a snow removal device 415 which may, for example, be a rotary blower, plow, or sweeper. The snow removal device 415 may be driven by engine power from the engine 40 via a power takeoff mechanism 420 to remove snow from a region near the snow removal vehicle 410 as the snow removal vehicle 410 is moving. The diagnostic system 12 may be used to diagnose vehicle malfunctions in the manner described above in connection with the vehicle 10, as well as to diagnose malfunctions of the specialized systems described above found on snow removal vehicles.

[0056] Advantageously, due to the utilization of a network architecture in the preferred embodiment, the diagnostic system is able to use sensors and other sources of information that are already provided on the vehicle, because it is able to interact with other vehicle control systems such as the engine control system, the anti-lock brake control system, the central tire inflation control system, and so on, via a network communication link. The fact that the diagnostic system is connected to these other systems, which are all typically capable of providing a vast array of status information, puts this status information at the disposal of the diagnostic system.

[0057] Further, due to the utilization of an intelligent display module in the preferred embodiment, it is possible for the intelligent display module to be connected to the network communication link and collect information as necessary for a variety of purposes. Thus, the preferred intelligent display module is microprocessor-based and is capable of executing firmware to provide additional functionality such as data logging, accident reconstruction, and a vehicle maintenance record. Again, this functionality can be achieved by taking advantage of the information available from the vehicle subsystems by way of the network architecture.

[0058] Moreover, by mounting the intelligent display module on board the vehicle in the preferred embodiment, for example, in an operator compartment, it is not necessary to bring the vehicle to a maintenance depot to have vehicle malfunctions diagnosed. The services offered by the intelligent display module are available wherever and whenever the vehicle is in operation.

[0059] Many other changes and modifications may be made to the present invention without department from the spirit thereof. The scope of these and other changes will become apparent from the appended claims.