The present invention relates to an auto diagnostic apparatus.
The majority of autos on the road today are computerized. In other words, the cars have control or processing units which receive and process information from sensors strategically placed on the internal combustion engine. These sensors include a throttle positioning sensor, a manifold absolute pressure sensor (a barometric and engine vacuum sensor), an oxygen sensor, an engine coolant sensor, an air charge temperature sensor to measure incoming air, an EGR valve positioning sensor, a vane air temperature sensor, and other sensors.
An auto technician conventionally chooses from one of two types of "scanners" to access information provided by such sensors. Each of the two types of scanners connects directly to the automobile's computer. Each of the two types of scanners is limited to only that information the vehicle's computer is programmed to share with the scanner.
One type of scanner provides "trouble codes," i.e., a numerical code followed by a description of the "diagnosis." The trouble code is generated by the central processing unit of the auto and is based on information provided by engine sensors. An example of a trouble code list is shown in Table 1. Trouble code information, such as that listed in Table 1, is typically available for most domestic and foreign cars.
TABLE 1 ______________________________________ TROUBLE CODE LIST ______________________________________ 33 EGR VALVE NOT OPENING 71 IDLE TRACKING SW STUCK OR CKT PROBLEM 95 FUEL PUMP CKT OPEN - ECA TO GROUND ______________________________________
A trouble code is typically generated only for major malfunctions that will blow the sensors wide open or cause the sensors to short out. Any intermediate outputs of the sensor are typically ignored by a trouble code scanner even though the values generated by the sensor may be in error. For example, a manifold absolute pressure sensor (barometric sensor) for an engine operating in the mile-high city of Denver may in fact provide an output voltage reflecting operation of the engine at sea level. A trouble code scanner typically does not note this "incorrect" value since operation at sea level is one of the many normal operating altitudes.
The second general type of scanner provides a "data stream," which conveys more useful information than a trouble code list. Like trouble code scanners, data stream scanners connect directly to the automobile's computer via a diagnostic plug. A data stream lists the sensors along with an output value for each of the sensors such as rpm, milliseconds, pressure, degrees, or voltage. An example of a data stream list is shown in Table 2. Such information is generally available for GM and Chrysler vehicles only, as these vehicles have diagnostic plugs.
TABLE 2 ______________________________________ DATA STREAM LIST VEHICLE INFORMATION ______________________________________ DIAGNOSTIC STATE 8 ALCL TROUBLE CODES SEE MANUAL ENGINE INFORMATION BLOCK ENGINE RPM 2125 DESIRED IDLE X10 10 02 STATE LEAN LOOP STATUS OPEN COOLANT TEMP. 023 DEG C. THROT. POS. SENSOR 1.70 V 02 SENSOR VOLTAGE 0.370 V INJECT. PULSE WID. 99.9 as BATTERY VOLTAGE 08.5 V MAP SENSOR 041 KPA MAP SENSOR 1.70 V IDLE AIR CONTROL 005 SPARK ADVANCE 37 DEB BLOCK LEARN 005 INTEGRATOR 005 EGR D.C. NO EGR DIAG.-POSITION YES MANIFOLD AIR 023 C CLEAR FLOOD MODE ON TRANSMISSION INFO. BLOCK VEHICLE SPEED 136 KPH T.C. CLUTCH OFF PARK/NEUTRAL OFF CRUISE CONTROL OFF SET-COAST NO RESUME-ACCEL YES BRAKE SWITCH OFF MISC. VEHICLE DATA INFO. CRANK OFF POWER STEERING NORM A/C REQUEST NO AIR/COND. CLUTCH OFF FAN ON 02 CROSS COUNTS 234 ______________________________________
Trouble code scanners are available for GM, Chrysler, and Ford vehicles. Data stream scanners are available for GM and Chrysler vehicles, and only recently have become available for newer Ford vehicles (some 1990 and newer models). To obtain a data stream on an older Ford vehicle, an auto technician uses a "break out box," i.e., a box that is connected in series between the male and female 60 pin connector of the Ford computer or central processing unit. The break out box is located at a remote, inconvenient, almost inaccessible location under the dash on most cars. The break out box typically includes 60 female connections, and an auto technician measures the voltage output between a predefined pair of female connections for each of the sensors. After obtaining a voltage reading, the auto technician translates the computer voltage reading into rpm, milliseconds, pressure, degrees, or voltage. Only one sensor at a time may be monitored. This process is time consuming and hence expensive to the car owner. It should be noted that Ford Motor Company markets, to its dealerships, an "Oasis" system which provides a data stream for newer Ford vehicles and which may not require a break out box, as some of the newer Ford vehicles now have diagnostic plugs. However, since pre-1990 Ford vehicles lacked such diagnostic plugs, such vehicles cannot be diagnosed with the "Oasis system."
Prior art diagnostic apparatus for providing trouble codes include the MT 2500 from Snap On Tool Corp., the Monitor 2000 & 4000 from the Owatonna Tool Corp., the Brainmaster from the Alltest Division of Triplitt Corp., and the ProLink 9000 from Micro Processor Systems, Inc. Break out boxes are available from the Ford Motor Co., Owatonna Tool Corp., and Thexton Manufacturing of Minneapolis. Micro Processor Systems, Inc. also markets an I.B.O.B. (Intelligent Break Out Box). It should also be noted that a clip for being electrically connected to an insulated wire through the insulation without destroying the insulation is marketed by J. S. Popper, Inc. of Little Ferry, N.J. This clip is identified by the designation "JP 8783 CLIP."